CN101651038B - Diffusion processing apparatus - Google Patents

Diffusion processing apparatus Download PDF

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Publication number
CN101651038B
CN101651038B CN2009101592585A CN200910159258A CN101651038B CN 101651038 B CN101651038 B CN 101651038B CN 2009101592585 A CN2009101592585 A CN 2009101592585A CN 200910159258 A CN200910159258 A CN 200910159258A CN 101651038 B CN101651038 B CN 101651038B
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rare earth
sintered magnet
volumes
magnet
diffusion
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CN101651038A (en
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吉村公志
森本英幸
小高智织
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Proterial Ltd
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Hitachi Metals Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets

Abstract

The invention relates to a diffusion processing apparatus, comprising a processing chamber; arranging a bulk body including a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb, along with the R-Fe-B based rare-earth sintered magnet body in a processing chamber; and providing an R-Fe-B based rare-earth sintered magnet body including, as a main phase, crystal grains of an R2Fe14B type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R; and heating the bulk body and the R-Fe-B based rare-earth sintered magnet body to a temperature of 700 [deg.]C to 1,000 [deg.]C, thereby diffusing the heavy rare-earth element RH into the R-Fe-B based rare-earth sintered magnet body while supplying the heavy rare-earth element RH from the bulk body to the surface of the R-Fe-B based rare-earth sintered magnet body.

Description

Diffusion processing apparatus
(the application is to be March 1, application number in 2007 the dividing an application for the patent application of " R-Fe-B based rare earth sintered magnet and manufacturing approach thereof " that be 200780000668.4 (PCT/JP2007/053892), denomination of invention the applying date.)
Technical field
The present invention relates to a kind of diffusion processing apparatus.
Background technology
With Nd 2Fe 14The Type B compound be the R-Fe-B based rare earth sintered magnet of principal phase known be the highest magnet of performance in the permanent magnet, voice coil motor (VCM) and hybrid power (hybrid) car that is used for hard disk drive carries with various motors such as motor and tame electrical article etc.When R-Fe-B based rare earth sintered magnet being used for various devices such as motor,, requiring excellent heat resistance and have the high-coercive force characteristic in order to adapt to the environment for use under the high temperature.
As the coercitive method that improves R-Fe-B based rare earth sintered magnet, adopt cooperate heavy rare earth dvielement RH as raw material, found the alloy that forms.According to this method, contain the R of light rare earth dvielement RL as rare earth element R 2Fe 14The rare earth element R of B phase can replace by enough heavy rare earth dvielement RH, therefore improves R 2Fe 14The crystallization magnetic anisotropy of B phase (determining coercitive internal physical quantity).Yet, R 2Fe 14The magnetic moment of the light rare earth dvielement RL of B in mutually and the magnetic moment of Fe are equidirectional, but the magnetic moment of the magnetic moment of heavy rare earth dvielement RH and Fe is a rightabout, and therefore, light rare earth dvielement RL is replaced manyly more by heavy rare earth dvielement RH, residual magnetic flux density B rDescend manyly more.
On the other hand, heavy rare earth dvielement RH is a scarce resource, therefore hopes to cut down its use amount.For the foregoing reasons, it is not preferred to replace the method for whole light rare earth dvielement RL with heavy rare earth dvielement RH.
In order just to show the coercitive effect of raising that heavy rare earth dvielement RH is brought through adding more a spot of heavy rare earth dvielement RH; Proposed following technical scheme: the principal phase containing more light rare earth dvielement RL is in the master alloy powder; Add the powder of the alloy contain more heavy rare earth dvielement RH, compound etc., form, sintering.According to this method, heavy rare earth dvielement RH is distributed in R mostly 2Fe 14Near the crystal boundary of B phase, therefore, can improve the R in the principal phase housing department efficiently 2Fe 14The crystallization magnetic anisotropy of B phase.The coercive force mechanism of production of R-Fe-B based rare earth sintered magnet is nucleation type (nucleation type); Therefore; Heavy rare earth dvielement RH is distributed near principal phase housing department (crystal boundary) mostly; Can improve the whole crystallization magnetic anisotropy of crystal grain thus, can avoid the nucleation of anti-magnetic region, its result improves coercive force.In addition, being helpless to improve coercitive crystal grain central part, the displacement of heavy rare earth dvielement RH can not take place, therefore, can suppress residual magnetic flux density B yet rReduction.
But, when reality is implemented this method, at sintering process (under commercial scale; Implement down at 1000 ℃～1200 ℃) in, the diffusion velocity of heavy rare earth dvielement RH increases, therefore; Heavy rare earth dvielement RH also can be diffused into the central part of crystal grain, and the result just is difficult to obtain the institutional framework of expectation.
In addition, as the coercitive additive method that improves R-Fe-B based rare earth sintered magnet, also studied stage at sintered magnet; After magnet surface coats the metal contain heavy rare earth dvielement RH, alloy, compound etc.; Heat-treat, make it diffusion, thus; Coercive force is recovered or raising, and make residual magnetic flux density not reduce (patent documentation 1, patent documentation 2 and patent documentation 3) so.
Patent documentation 1 discloses at least a in the Ti that being formed on the grinding face of sintered magnet contains 1.0 atom %～50.0 atom %, W, Pt, Au, Cr, Ni, Cu, Co, Al, Ta, Ag, and all the other be the alloy firm layer of R ' (R ' be among Ce, La, Nd, Pr, Dy, Ho, the Tb at least a).
Patent documentation 2 discloses metallic element R (this R be Y be selected from one or more of rare earth element among Nd, Dy, Pr, Ho, the Tb) is diffused to more than the degree of depth suitable with the radius of the crystal grain that exposes on the surface of small-sized magnet; Thus; Carry out modification to processing rotten impaired, improve (BH) max.
It is that magnet surface below the 2mm forms with the rare earth element is the chemical vapor deposition films of main body that patent documentation 3 discloses at thickness, and the magnet characteristic is recovered.
In the patent documentation 4, in order to recover the coercive force that R-Fe-B is small sintered magnet and powder, the absorption method of rare earth element is disclosed.In the method, after will adsorbing metal (the lower rare earth metals of boiling point of Yb, Eu, Sm etc.) and R-Fe-B and being small sintered magnet or powder, carry out stirring even in a vacuum heat treatment of heating on one side.Through this heat treatment, rare earth metal is coated on magnet surface, is diffused into inside simultaneously.In addition, in patent documentation 4, also put down in writing the execution mode that adsorbs the high rare earth metal (for example Dy) of boiling point.Use in the execution mode of Dy etc. at this,, selectively Dy etc. is heated to high temperature through the high-frequency heating mode; For example, the boiling point of Dy is 2560 ℃, and the Yb of 1193 ℃ of boiling points is heated to 800 ℃～850 ℃; With common impedance heated; Can not fully heat, therefore, consider that Dy will be heated to the temperature above 1000 ℃ at least.In addition, also having put down in writing R-Fe-B is that the temperature of small sintered magnet and powder preferably remains on 700～850 ℃.
Patent documentation 1: japanese kokai publication sho 62-192566 communique
Patent documentation 2: TOHKEMY 2004-304038 communique
Patent documentation 3: TOHKEMY 2005-285859 communique
Patent documentation 4: TOHKEMY 2004-296973 communique
Patent documentation 1, patent documentation 2 and patent documentation 3 disclosed prior aries; All be as purpose with the sintered magnet surface of recovering the processing deterioration; Therefore, be limited to the near surface of sintered magnet to the range of scatter of the metallic element of diffusion inside from diffusion into the surface.So,, almost can not obtain coercitive raising effect to the magnet more than the thickness 3mm.
On the other hand, in patent documentation 4 disclosed prior aries, rare earth metals such as Dy are heated to the temperature of abundant gasification, carry out film forming, therefore, film forming speed is higher than the diffusion velocity in the magnet utterly, on magnet surface, forms thick Dy film.Its result in magnet top layer zone (zone of the depths of μ m from surface to tens), is an actuating force with the big concentration difference of the Dy concentration between the interface of Dy film and sintered magnet, and Dy also can be diffused in the principal phase inevitably, finally makes residual magnetic flux density B rReduce.
In addition, in the method for patent documentation 4, the part (for example, the inwall of vacuum chamber) when film forming is handled beyond the inner magnet of device is also piled up a large amount of rare earth metals, therefore runs counter to the resources conservation as the heavy rare earth dvielement of precious resource.
In addition; Be in the execution mode of object with low boiling rare earth metals such as Yb, each R-Fe-B is that the coercive force of small magnet recovers really, still; During diffusion heat treatments; R-Fe-B based magnet and absorption metal alloying, or be difficult to each other after handling separate, in fact be difficult to avoid unreacted absorption metal (RH) to remain in the sintered magnet surface.This not only makes the magnetic components ratio in the magnet formed body descend; Cause the magnet characteristic to weaken, and owing to the very strong activity of rare earth metal itself is easy to take place oxidation, in practical environment; Unreacted absorption metal is easy to become the starting point of corrosion, and is therefore not preferred.In addition; Because the rotation and the vacuum heat that need be used to mix stirring simultaneously, therefore, need keep thermal endurance, pressure (air tightness), be assembled with the special device of rotating mechanism simultaneously; When making in batches, existing problems aspect equipment investment and stay in grade manufacturing.In addition, when the absorption raw material uses powder, become the major reason that causes safety issue (catching fire) and manufacturing process to waste time and energy cost is improved with harmful.
In addition; Be in the execution mode of object with the higher boiling point rare earth metal that contains Dy; Owing to utilize high frequency will adsorb raw material and magnet heating; Difficult realization only is heated to rare earth metal abundant temperature and magnet is remained on the low temperature that magnetic characteristic is not had effect, and magnet only limits to be difficult to guide the pulverulence or the atomic little form of heating.
Summary of the invention
The present invention is the invention of making in order to address the above problem; Its purpose is to provide a kind of a spot of heavy rare earth dvielement RH that utilizes efficiently; Even magnet is thicker; Also can in the scope of magnet integral body, make heavy rare earth dvielement RH be diffused into the R-Fe-B based rare earth sintered magnet of the housing department of main phase grain.
The manufacturing approach of R-Fe-B based rare earth sintered magnet of the present invention comprises: prepare to have and contain the R of light rare earth dvielement RL (among Nd and the Pr at least a) as main rare earth element R 2Fe 14The Type B compound crystal grain is as the operation (a) of the R-Fe-B based rare earth sintered magnet of principal phase; Volume (the バ Le Network) body that will contain heavy rare earth dvielement RH (be selected among Dy, Ho and the Tb at least a) is configured in the operation (b) in the process chamber with above-mentioned R-Fe-B based rare earth sintered magnet; With through be heated to above-mentioned volumes and above-mentioned R-Fe-B based rare earth sintered magnet more than 700 ℃, below 1000 ℃; Heavy rare earth dvielement RH is supplied to the surface of above-mentioned R-Fe-B based rare earth sintered magnet from above-mentioned volumes, make above-mentioned heavy rare earth dvielement RH be diffused into the operation (c) of the inside of above-mentioned R-Fe-B based rare earth sintered magnet simultaneously.
In a preferred embodiment, in above-mentioned operation (c), above-mentioned volumes and above-mentioned R-Fe-B based rare earth sintered magnet are configured in the above-mentioned process chamber non-contiguously, and their equispaced is set in the scope more than the 0.1mm, below the 300mm.
In a preferred embodiment, in above-mentioned operation (c), the temperature difference of the temperature of above-mentioned R-Fe-B based rare earth sintered magnet and the temperature of above-mentioned volumes is in 20 ℃.
In a preferred embodiment, in above-mentioned operation (c), the pressure of the atmosphere gas in the above-mentioned process chamber is adjusted to 10 -5In the scope of～500Pa.
In a preferred embodiment, in above-mentioned operation (c), the temperature of above-mentioned volumes and above-mentioned R-Fe-B based rare earth sintered magnet was remained in the scope more than 700 ℃, below 1000 ℃ 10 minutes～600 minutes.
In a preferred embodiment, above-mentioned sintered magnet contain that 0.1 quality % is above, the heavy rare earth dvielement RH below the 5.0 quality % (be selected among Dy, Ho and the Tb at least a).
In a preferred embodiment, the content of the heavy rare earth dvielement RH of above-mentioned sintered magnet is more than the 1.5 quality %, below the 3.5 quality %.
In a preferred embodiment, above-mentioned volumes contains the alloy of heavy rare earth dvielement RH and element X (be selected among Nd, Pr, La, Ce, Al, Zn, Sn, Cu, Co, Fe, Ag and the In at least a).
In a preferred embodiment, above-mentioned element X is Nd and/or Pr.
In a preferred embodiment, in above-mentioned operation (c) afterwards, comprise above-mentioned R-Fe-B based rare earth sintered magnet is implemented to append heat treated operation.
The manufacturing approach of another kind of R-Fe-B based rare earth sintered magnet of the present invention comprises: make to have and contain the formed body of light rare earth dvielement RL (among Nd and the Pr at least a) as the R-Fe-B based rare earth ferromagnetic powder of main rare earth element R; Relative with the volumes that contains heavy rare earth dvielement RH (be selected among Dy, Ho and the Tb at least a), be configured in the operation (A) in the process chamber; Through in above-mentioned process chamber, carrying out sintering, manufacturing has R 2Fe 14The Type B compound crystal grain is as the operation (B) of the R-Fe-B based rare earth sintered magnet of principal phase; With through in above-mentioned process chamber; Above-mentioned volumes and above-mentioned R-Fe-B based rare earth sintered magnet are heated; Heavy rare earth dvielement RH is supplied to the surface of above-mentioned R-Fe-B based rare earth sintered magnet from above-mentioned volumes, make above-mentioned heavy rare earth dvielement RH be diffused into the operation (C) of the inside of above-mentioned R-Fe-B based rare earth sintered magnet simultaneously.
In a preferred embodiment, in the above-mentioned operation (B), the vacuum degree in the above-mentioned process chamber is made as 1～10 5Pa is made as 1000～1200 ℃ with the atmosphere temperature in the above-mentioned process chamber, carries out 30 minutes～600 minutes sintering.
In a preferred embodiment, in the above-mentioned operation (C), the vacuum degree in the above-mentioned process chamber is made as 1 * 10 -5Pa～1Pa is made as 800～950 ℃ with the atmosphere temperature in the above-mentioned process chamber, carries out 10 minutes～600 minutes heat treated.
In a preferred embodiment, in above-mentioned operation (B) afterwards, comprise that atmosphere temperature in the above-mentioned process chamber reaches below 950 ℃ after, the vacuum degree in the above-mentioned process chamber is adjusted to 1 * 10 - 5The operation of Pa～1Pa (B ').
In a preferred embodiment, in above-mentioned operation (B) afterwards, also comprise the vacuum degree in the above-mentioned process chamber is made as 1 * 10 -5Pa～1Pa is made as 1000～1200 ℃ with the atmosphere temperature in the above-mentioned process chamber, carries out 30～300 minutes heat treated, makes the atmosphere temperature in the above-mentioned process chamber be made as the operation (B ") below 950 ℃ then.
R-Fe-B based rare earth sintered magnet of the present invention is to adopt above-mentioned any having of manufacturing approach manufacturing to contain the R of light rare earth dvielement RL (among Nd and the Pr at least a) as main rare earth element R 2Fe 14The Type B compound crystal grain is as the R-Fe-B based rare earth sintered magnet of principal phase; Contain through crystal boundary diffusion and be imported into inner heavy rare earth dvielement RH (be selected from Dy, Ho and the Tb at least a) from the surface; At the zone, top layer of the 100 μ m from above-mentioned surface to the degree of depth, above-mentioned R 2Fe 14Concentration and the above-mentioned R of the heavy rare earth dvielement RH of Type B compound crystal grain central portion 2Fe 14Between the concentration of the heavy rare earth dvielement RH of the crystal boundary phase of Type B compound crystal grain, produce the above difference of 1 atom %.
The invention effect
In the present invention; Through carrying out the crystal boundary diffusion of heavy rare earth metalloid RH (be selected among Dy, Ho and the Tb at least a); Heavy rare earth dvielement RH is supplied to the inner depth location of sintered magnet, at the principal phase housing department, can be efficiently with heavy rare earth dvielement RH displacement light rare earth dvielement RL.Its result can suppress residual magnetic flux density B rReduction, and make coercive force H CJImprove.
Description of drawings
Fig. 1 is applicable to a routine sectional view of the configuration relation of RH volumes and sintered magnet in formation and the container handling of container handling of R-Fe-B based rare earth method of manufacturing sintered magnet of the present invention for expression.
Fig. 2 is the curve chart of the time variation of atmosphere temperature in the process chamber in expression sintering of the present invention, the diffusing procedure and atmosphere gas pressure.Single-point line expression atmosphere gas pressure in the curve, solid line is represented atmosphere temperature.
Fig. 3 is the curve chart of another time variation of atmosphere temperature in the process chamber in expression sintering of the present invention, the diffusing procedure and atmosphere gas pressure.Single-point line expression atmosphere gas pressure in the curve, solid line is represented atmosphere temperature.
Fig. 4 is the photo of cross section EPMA analysis result of sample 2 gained of the expression embodiment of the invention, (a) and (b), (c) and reflection (mapping) photo that (d) is respectively the distribution of representing BEI (reflection electronic ray image), Nd, Fe and Dy.
Fig. 5 is the photo of cross section EPMA analysis result of sample 4 gained of the expression embodiment of the invention, (a) and (b), (c) and the reflection photo that (d) is respectively the distribution of representing BEI (reflection electronic ray image), Nd, Fe and Dy.
Fig. 6 is the mensuration result's of the Dy concentration of principal phase central portion and the crystal boundary triple point of the sample 2,3 of the expression embodiment of the invention curve chart.
Fig. 7 is the mensuration result's of the Dy concentration of principal phase central portion and the crystal boundary triple point of the sample 4,5 of the expression embodiment of the invention curve chart.
Fig. 8 (a) is expression residual magnetic flux density B rWith the curve chart of the relation of treatment temperature, (b) be expression coercive force H CJCurve chart with the relation of treatment temperature.
Fig. 9 (a) is expression residual magnetic flux density B rWith the curve chart of the relation in processing time, (b) be expression coercive force H CJCurve chart with the relation in processing time.
Figure 10 (a) is expression residual magnetic flux density B rWith the curve chart of the relation of atmosphere pressures, (b) be expression coercive force H CJCurve chart with the relation of atmosphere pressures.
The sectional view of the configuration that the Mo package body that Figure 11 uses for the expression embodiment of the invention is interior.
Figure 12 is the photo of the outward appearance observed result of Mo package body inwall after the expression heat treatment.
The sectional view of the configuration that the Mo package body that Figure 13 uses for the expression embodiment of the invention is interior.
Figure 14 is the figure of the configuration relation of Dy plate in the expression embodiment of the invention and sintered magnet.
Figure 15 is the distance of expression from magnet to the Dy plate and the figure of the configuration relation of sintered magnet.
Figure 16 is the sectional view of the configuration relation of expression Dy plate and sintered magnet.
Figure 17 is the curve chart of the relation of the configuration of expression Dy plate and magnet characteristic.
The photo of the EPMA analysis result on the sintered magnet surface after the heat treatment when Figure 18 only disposes the Dy plate for expression under sintered magnet; (a) be the photo of analysis result of the upper central portion of expression sintered magnet, (b) be the photo of the analysis result of the following central portion of expression sintered magnet.
Figure 19 is the photo of expression embodiment 7.
Figure 20 is the sectional view of the configuration relation of Dy-X alloy sheets in the employed container handling in the manufacturing of expression embodiment 8 and sintered magnet.
Figure 21 (a) and (b) and the residual magnetic flux density B that (c) is respectively the magnet sample that expression makes according to manufacturing approach of the present invention r, coercive force H CJAnd rectangularity (H k/ H CJ) figure.
Figure 22 (a) is the figure of the configuration relation of expression sintered magnet and Dy plate, (b) is the figure of the crystal orientation of expression sintered magnet.
The residual magnetic flux density B that Figure 23 (a) measures for expression embodiment 9 rCurve chart, the coercive force H that (b) measures for expression embodiment 9 CJCurve chart.
Figure 24 is expression embodiment 9 resulting coercive force H CJCurve chart with the relation of stock removal.
Figure 25 (a) and the stereogram that (b) covers by the Nb paper tinsel for which part of sintered magnet surface among the expression embodiment 10.
Figure 26 (a) shows the coercive force variation delta H that the mark device is measured for expression composition L～P's by B-H CJCurve chart, (b) be their residual magnetic flux density variation delta B of expression rCurve chart.
Figure 27 (a) is expression and 12 residual magnetic flux density B that sample is relevant rThe curve chart of measured value, (b) for expression with the relevant coercive force H of sample CJThe curve chart of measured value.
Symbol description
2: sintered magnet; The 4:RH volumes; 6: process chamber; The net of 8:Nb system
Embodiment
R-Fe-B based rare earth sintered magnet of the present invention contains the heavy rare earth dvielement RH that is imported into inside through the crystal boundary diffusion from the sintered body surface.Wherein, heavy rare earth dvielement RH is selected from least a among Dy, Ho and the Tb.
R-Fe-B based rare earth sintered magnet of the present invention is fit to through heavy rare earth dvielement RH is supplied to the sintered magnet surface from heavy rare earth class volumes (RH volumes) heavy rare earth dvielement RH made to diffusion inside from the surface of sintered body.
In manufacturing approach of the present invention; Volumes and the rare-earth sintered magnet of heavy rare earth dvielement RH through being difficult to gasification (distillation) be heated to more than 700 ℃, below 1000 ℃; The growth rate that the gasification (distillation) of RH volumes is controlled at the RH film is not much larger than the degree of RH to the inner diffusion velocity of magnet; Simultaneously, make the heavy rare earth dvielement RH that flies to the sintered magnet surface be diffused into magnet inside rapidly.Temperature range more than 700 ℃, below 1000 ℃ is the temperature that can produce the gasification (distillation) of heavy rare earth dvielement RH hardly, also is the active temperature of carrying out of rare earth element diffusion in the R-Fe-B based rare earth sintered magnet.Therefore, the heavy rare earth dvielement RH that flies to magnet surface has precedence in the magnet surface film forming, can promote to the inner crystal boundary diffusion of magnet.
In addition, in this manual, will heavy rare earth dvielement RH be supplied to the sintered magnet surface from heavy rare earth class volumes (RH volumes) sometimes, and make heavy rare earth class RH simply be called " vapor deposition diffusion " to the phenomenon of diffusion inside simultaneously from the surface of sintered magnet.According to the present invention, heavy rare earth dvielement RH is to be higher than the speed that heavy rare earth dvielement RH is diffused into the speed (speed) of the principal phase inside that is positioned at the sintered magnet near surface, to magnet diffusion inside, infiltration.
Think that at present the gasification (distillation) of heavy rare earth dvielement RH such as Dy need be heated to above 1000 ℃ high temperature, and think and pine for being difficult to make Dy to separate out in magnet surface in adding more than 700 ℃, below 1000 ℃.But, can know according to the inventor's experiment: opposite with existing prediction, even more than 700 ℃, below 1000 ℃, also can supply with heavy rare earth dvielement RH to the rare earth element magnet that is oppositely arranged, make it diffusion.
Be formed on the surface of sintered magnet at the film (RH film) of heavy rare earth dvielement RH after, be diffused in the inner prior art of sintered magnet through heat treatment, in the zone, top layer that joins with the RH film, " intracrystalline diffusion " progress is remarkable, finally makes the magnet deterioration in characteristics.Otherwise; In the present invention; Be suppressed under the lower state in the growth speed with the RH film, RH supplies to the sintered magnet surface with the heavy rare earth dvielement, and the temperature with sintered magnet remains on the level that is suitable for spreading simultaneously; Therefore, the heavy rare earth dvielement RH that flies to magnet surface passes through crystal boundary diffusion rapid permeability to sintered magnet inside.Therefore, even in the zone, top layer, " crystal boundary diffusion " also has precedence over " intracrystalline diffusion " and takes place, and can suppress residual magnetic flux density B rReduction, effectively improve coercive force H CJ
Because the coercive force mechanism of production of R-Fe-B based rare earth sintered magnet is a nucleation type, therefore, when the crystallization magnetic anisotropy in the principal phase housing department raises, suppress near the nucleation of the anti-magnetic region mutually of crystal boundary in the principal phase, the result effectively improves the coercive force H of principal phase integral body CJIn the present invention, not only magnetic sintered body near surface zone, and the zone from the magnet surface to the depths also can form heavy rare earth class displacement layer at the principal phase housing department, so magnet crystallization magnetic anisotropy on the whole increases, and fully improves the whole coercive force H of magnet CJTherefore, according to the present invention, the heavy rare earth dvielement RH amount that is consumed can make heavy rare earth dvielement RH diffusion, infiltrate into sintered body inside, through concentrating the layer that heavy rare earth dvielement RH is arranged efficient formation of principal phase housing department, can suppress residual magnetic flux density B rReduction, improve coercive force H simultaneously CJ
As the heavy rare earth dvielement RH that replaces at principal phase housing department and light rare earth dvielement RL, consider the easy generation property, cost of vapor deposition diffusion etc., most preferably Dy.Wherein, Tb 2Fe 14The crystallization magnetic anisotropy of B compares Dy 2Fe 14The crystallization magnetic anisotropy of B is high, has the Nd of being about 2Fe 14Therefore the crystallization magnetic anisotropy of 3 times of sizes of B, when making Tb vapor deposition when diffusion, can be implemented in most effectively under the situation that the residual magnetic flux density of sintered magnet do not descend and improve coercive force.When using Tb, compare during with use Dy, preferably under the high temperature condition of high vacuum degree, carry out the vapor deposition diffusion.
Can know by above-mentioned explanation, in the present invention, not necessarily must add heavy rare earth dvielement RH in the stage of raw alloy.That is, prepare to contain the known R-Fe-B based rare earth sintered magnet of light rare earth dvielement RL (among Nd and the Pr at least a) as rare earth element R, with heavy rare earth dvielement RH from its diffusion into the surface to magnet inside.Only existing heavy rare earth dvielement layer is formed at the situation of magnet surface; Even raising diffusion temperature; Heavy rare earth dvielement RH also is difficult to be diffused into the inner depths of magnet, but according to the present invention, through the crystal boundary diffusion of heavy rare earth dvielement RH; Even at the housing department that is positioned at the inner principal phase of sintered magnet, heavy rare earth dvielement RH also can supply with efficiently.Certainly, the present invention is that sintered magnet also is suitable in the stage of raw alloy for the R-Fe-B that adds heavy rare earth dvielement RH.Wherein,, add a large amount of heavy rare earth dvielement RH and can not give full play to effect of the present invention, therefore, can add more a spot of relatively heavy rare earth dvielement RH in the stage of raw alloy.
The preference of DIFFUSION TREATMENT of the present invention then, is described with reference to Fig. 1.Fig. 1 representes the configuration example of sintered magnet 2 and RH volumes 4.In example shown in Figure 1, in the inside of the process chamber that is made up of high melting point metal materials 6, sintered magnet 2 and RH volumes 4 are oppositely arranged across predetermined distance.The process chamber 6 of Fig. 1 has parts that keep a plurality of sintered magnets 2 and the parts that keep RH volumes 4.In the example of Fig. 1, the RH volumes 4 of sintered magnet 2 and top is kept by the net 8 of Nb system.Keeping the formation of sintered magnet 2 and RH volumes 4 to be not limited to above-mentioned example, can be any formation.Wherein, should not adopt the formation of interdicting with between sintered magnet 2 and the RH volumes 4." relatively " among the application is meant does not have blocking and the state on opposite between sintered magnet and the RH volumes.In addition, " the relative configuration " need not main surperficial parallel configuration.
Through in not shown heater, process chamber 6 being heated, the temperature of process chamber 6 is risen.At this moment, the adjustment of process chamber 6 is preferably 850 ℃～950 ℃ scope to for example 700 ℃～1000 ℃.In this temperature province, the vapour pressure of heavy rare earth metalloid RH only has seldom, almost completely not gasification.General knowledge according to prior art is thought: in such temperature range, can not be supplied to surface and the film forming of sintered magnet 2 by the heavy rare earth dvielement RH of RH volumes 4 evaporation.
But; The inventor finds: the disposed adjacent through not contacting sintered magnet 2 and RH volumes 4; The heavy rare earth metalloid is separated out on the surface of sintered magnet 2 with the low rate of a few μ m (for example 0.5～5 μ m/Hr) per hour; And, through with the adjustment of sintered magnet 2 to identical with the temperature of RH volumes 4 or than in its high proper temperature scope, can make the direct deep diffusion of heavy rare earth metalloid RH separated out by gas phase inside to sintered magnet 2.The crystal boundary that this temperature range passes to sintered magnet 2 for the RH metal is the preferred temperature province of diffusion inside in opposite directions, effectively realize the RH metal slowly separate out and to the inner diffusion rapidly of magnet.
In the present invention; As stated; The RH that a small amount of gasification is only arranged is separated out on the sintered magnet surface with low rate, therefore needn't separate out, surpass 1000 ℃ high temperature with being heated in the process chamber, also needn't apply voltage to sintered magnet or RH volumes like the RH of existing gas phase film forming.
In the present invention, as stated, in the gasification that suppresses the RH volumes, distillation, make the heavy rare earth dvielement RH that flies to the sintered magnet surface be diffused into magnet inside rapidly.For this reason, preferably the temperature with the RH volumes is set in the scope more than 700 ℃, below 1000 ℃, and the temperature of sintered magnet is set in the scope more than 700 ℃, below 1000 ℃.
The interval of sintered magnet 2 and RH volumes 4 is set in 0.1mm～300mm.This is preferably more than the 1mm at interval, below the 50mm, more preferably below the 20mm, further is preferably below the 10mm.As long as can keep state at a distance of such distance, about the configuration relation of sintered magnet 2 and RH volumes 4 can be configured to, about, move relative to each other in addition.Wherein, the sintered magnet 2 and the distance of RH volumes 4 that are preferably in the vapor deposition DIFFUSION TREATMENT do not change.For example, while preferably sintered magnet is not contained in and stirs the mode of handling in the tumbler.In addition, because as long as the RH of gasification just can form uniform RH atmosphere in aforesaid distance range, therefore regardless of the area of relative face, the face of the narrowest area is relative each other.According to inventor's research, with the direction of magnetization (c direction of principal axis) of sintered magnet 2 when the RH volumes vertically is set, be diffused into to the RH peak efficiency inside of sintered magnet 2.Think this be because transmit mutually through the crystal boundary of sintered magnet 2 at RH, during to diffusion inside, the diffusion velocity of the direction of magnetization is bigger than the diffusion velocity of its vertical direction.The reason that the diffusion velocity of the direction of magnetization is bigger than the diffusion velocity of its vertical direction is inferred as due to the anisotropy difference of crystalline texture.
Under the situation of existing evaporation coating device, the mechanism on every side that deposition material is supplied with part forms obstacle, need supply with part to deposition material and shine electron ray or ion, therefore, need supply with partly and between the object being treated at deposition material suitable distance is set.Therefore, can not be as deposition material be supplied with part (RH volumes 4) and object being treated (sintered magnet 2) disposed adjacent according to the inventionly.Only if its result is considered to deposition material is heated to sufficiently high temperature and fully gasification, otherwise can not on object being treated, fully supply with deposition material.
Otherwise, in the present invention, need not to be used to make the special entity of deposition material gasification (distillation), through the whole temperature in control and treatment chamber, the RH metal is separated out at magnet surface.In addition, " process chamber " in this specification broadly comprises the space of configuration sintered magnet 2 and RH volumes 4, refers to the process chamber of heat-treatment furnace sometimes, also refers to be housed in the container handling in such process chamber sometimes.
In addition, in the present invention, the amount of vaporization of RH metal seldom; But because noncontact and being configured in the very near distance between sintered magnet and the RH volumes 4; Therefore, the RH metal of gasification is separated out on the sintered magnet surface efficiently, seldom attached on wall in the process chamber etc.In addition, the wall in the process chamber then will gasify attached to the RH metal on the wall so long as do not processed with the material of RH reaction by heat-resisting alloy such as Nb or pottery etc. once more, finally separates out on the sintered magnet surface.Therefore, can suppress wasting as the heavy rare earth dvielement RH of precious resource.
In the temperature ranges of the diffusing procedure that the present invention carries out, the not fusion of RH volumes is softening, and from its surface, RH metal generating gasification (distillation) therefore, utilizes the single treatment operation not make the face shaping generation great variety of RH volumes, can use repeatedly.
In addition, because RH volumes and sintered magnet disposed adjacent, therefore in having the process chamber of same volume, the amount of the sintered magnet that can carry increases, and stow efficient is high.In addition,, therefore can use common vacuum heat treatment furnace flexibly, can avoid the raising of manufacturing cost, have practicality owing to need not large-scale plant.
Be preferably torpescence atmosphere in process chamber during heat treatment.In this manual, " torpescence atmosphere " is meant the state that comprises vacuum or be full of inactive gas.In addition, " inactive gas " for example is argon gas rare gas such as (Ar), still, so long as can avoid taking place between RH volumes and the sintered magnet gas of chemical reaction, all is included in " inactive gas ".The pressure of inactive gas is decompressed to and is shown as the value of forcing down than atmosphere.When the atmosphere pressures in the process chamber and atmospheric pressure near the time; Be difficult to the RH metal is supplied with to the sintered magnet surface from the RH volumes; Diffusing capacity is according to carrying out control rate from magnet surface to the diffusion velocity of inside, and therefore, as long as the atmosphere pressures in the process chamber is for example 10 2Be below the Pa fully, even the decline degree of the atmosphere pressures in the process chamber on this, does not have big influence to the diffusing capacity (coercive force raising degree) of RH metal yet.Diffusing capacity is with respect to pressure, and is more responsive to the temperature of sintered magnet.
The RH metal that flies to the surface of sintered magnet and separate out with the difference of the RH concentration at the heat of atmosphere and magnet interface as actuating force, from crystal boundary mutually to the magnet diffusion inside.At this moment, R 2Fe 14The part of the light rare earth dvielement RL of B in is mutually replaced through the heavy rare earth dvielement RH from the magnet surface scattering and permeating.Its result is at R 2Fe 14The housing department of B phase forms and concentrates the layer that heavy rare earth dvielement RH is arranged.
Through the formation of such RH enriched layer, can improve the crystallization magnetic anisotropy of principal phase housing department, improve coercive force H CJThat is, through the use of less RH metal, heavy rare earth dvielement RH scattering and permeating forms denseization of RH layer to the magnet deep inside at the principal phase housing department efficiently, therefore, is suppressing residual magnetic flux density B rReduction the time, can improve the whole coercive force H of magnet CJ
According to prior art, heavy rare earth dvielement RH such as Dy compare especially high with heavy rare earth dvielement RH to the speed (diffusion velocity) of sintered magnet diffusion inside in the speed (the growth speed of film) of sintered magnet surface sediment.Therefore, not only form the RH film more than a few μ m of thickness, and heavy rare earth dvielement RH is diffused into sintered magnet inside from this RH film on the sintered magnet surface.Be not the heavy rare earth dvielement RH that supplies with from gas phase but from the RH film of solid phase not only in the crystal boundary diffusion, and carry out the intracrystalline diffusion in the principal phase inside in the zone, top layer that is positioned at sintered magnet, cause residual magnetic flux density B rReduction.Also there is the intracrystalline diffusion of heavy rare earth dvielement RH principal phase inside; The zone that the difference of RH concentration disappears between principal phase and crystal boundary phase is limited to zone, sintered magnet top layer (for example below the thickness 100 μ m); When the very thin thickness of magnet integral body, can not avoid residual magnetic flux density B rReduction.
But,, behind heavy rare earth dvielement RH such as the Dy that supplies with from gas phase and the sintered magnet surface collision, spread rapidly in that sintered magnet is inner according to the present invention.This means before heavy rare earth dvielement RH is diffused into the principal phase inside that is positioned at the zone, top layer, through the crystal boundary phase, be penetrated into the deep inside of sintered magnet with higher diffusion velocity.
According to the present invention, from the zone, top layer of surface to the degree of depth 100 μ m of sintered magnet, R 2Fe 14Concentration and the R of the heavy rare earth dvielement RH of the central portion of Type B compound crystal grain 2Fe 14Between the concentration of the heavy rare earth dvielement RH of the crystal boundary of Type B compound crystal grain in mutually, produce the above difference of 1 atom %.In order to suppress residual magnetic flux density B rReduction, be preferably formed the concentration difference of 2 atom %.
In addition, the content of the RH of diffusion preferably is set in the scope more than 0.05%, below 1.5% in the whole weight ratio of magnet.When being higher than 1.5%, residual magnetic flux density B might can not be suppressed rReduction, and when being lower than 0.1%, coercive force H CJThe raising effect little.Under said temperature zone and pressure,, can reach 0.1%～1% diffusing capacity through 10～180 minutes heat treatment.Processing time be meant RH volumes and sintered magnet temperature reach more than 700 ℃, below 1000 ℃ and pressure reach 10 -5Pa is above, the time below the 500Pa, is not that only expression must keep specific temperature, the time of pressure.
The surface state of sintered magnet is preferably RH and is easy to scattering and permeating, more near the surface state of metallic state, is preferably activation processing such as using acid cleaning or injection (blast) processing in advance.Wherein, in the present invention, when heavy rare earth dvielement RH gasification, when under activated state, covering the sintered magnet surface, with than forming the also high speed of solid layer to the sintered magnet diffusion inside.Therefore, the sintered magnet surface can be for example after sintering circuit or cut off the state that continues oxidation after machining.
According to the present invention, since main through crystal boundary mutual-assistance heavy rare earth dvielement RH diffusion, so, can make heavy rare earth dvielement RH efficiently to the darker position diffusion in magnet inside through regulating the processing time.
In addition, through regulating the pressure of handling atmosphere, can control the evaporation rate of heavy rare earth dvielement RH; Therefore, for example, when when sintering circuit, being configured in the RH volumes in the device; When sintering circuit; Atmosphere gas pressure based on higher relatively not only can suppress the evaporation of RH, but also can the acceleration of sintering reaction.At this moment, after sintering finishes,, promote evaporation, the diffusion of RH, can cross and use same equipment to implement sintering circuit and coercive force raising operation continuously through reducing atmosphere gas pressure.For such method, in execution mode 2, be elaborated.
The not special restriction of the shape of RH volumes, size can be tabular, also can be amorphous (stone shape).Also can there be a large amount of apertures (about diameter several 10 μ m) on the RH volumes.The RH volumes is preferably formed by RH metal that contains at least a heavy rare earth dvielement RH or the alloy that contains RH.In addition, the vapour pressure of the material of RH volumes is high more, and the RH import volume of time per unit is big more, and efficient is just high more.Contain oxide, fluoride, nitride of heavy rare earth dvielement RH etc., it is extremely low that its vapour pressure becomes, and in this condition and range (temperature, vacuum degree), causes vapor deposition, diffusion hardly.Therefore, even form the RH volumes, do not reach coercive force yet and improve effect by the oxide that contains heavy rare earth dvielement RH, fluoride, nitride etc.
According to the present invention, can provide for the for example thick magnet more than the thickness 3mm, use heavy rare earth dvielement RH, the raising residual magnetic flux density B of very small amount rWith coercive force H CJEven both at high temperature, can not weaken the high-performance magnet of magnetic characteristic yet.This high-performance magnet is for realizing that microminiature, high capacity motor have very great help.Show significantly especially in the magnet of effect of the present invention below thickness 10mm that utilizes crystal boundary to spread.
In the present invention, both can make heavy rare earth dvielement RH scattering and permeating, also can make heavy rare earth dvielement RH scattering and permeating from the part on sintered magnet surface from sintered magnet surface integral body.A part for example also can adopt the RH scattering and permeating part of not wanting to make the RH scattering and permeating the sintered magnet to be sheltered etc., implement heat treatment with the method that said method is same from sintered magnet surface.According to such method, can access part and improve coercive force H CJMagnet.
Magnet through the vapor deposition diffusing procedure of the present invention is implemented to append heat treatment again, can further improve coercive force (H CJ).Appending heat treated condition (treatment temperature, time) can be the condition same with the vapor deposition diffusion conditions, preferably under 700 ℃～1000 ℃ temperature, keeps 10 minutes～600 minutes.
Append heat treatment and can after diffusing procedure finishes, the Ar dividing potential drop be brought up to 10 3About Pa, directly only heat-treat under the situation of heavy rare earth dvielement RH evaporation avoiding, can also after accomplishing diffusing procedure, not dispose under the RH evaporation source, according to only heat-treating with the same condition of diffusing procedure once more.
Through implementing the vapor deposition diffusion, improve the mechanical strengths such as rupture strength in the sintered magnet, therefore preferred aspect practical.By inference, this is when vapor deposition spreads, and because of causing the opening of the strain that sintered magnet is inherent, or the recovery of processing deterioration layer, or heavy rare earth dvielement RH diffusion, makes the result of principal phase and crystal boundary crystallization matching raising mutually.When principal phase and crystal boundary crystallization matching mutually improved, crystal boundary was reinforced, and the patience of intercrystalline fracture is improved.
Below, the preferred implementation of the manufacturing approach of R-Fe-B based rare earth sintered magnet of the present invention is described.
(execution mode 1)
[raw alloy]
At first, prepare to contain light rare earth dvielement RL, the B (boron) of 0.6 quality %～1.6 quality %, all the other alloys that 25 quality % are above, 40 quality % are following for Fe and inevitable impurity.Both can use C (carbon) to replace a part of B, and also can use other transition metal (for example Co or Ni) to replace a part of Fe (below the 50 atom %).According to various purposes, this alloy can also contain at least a interpolation element M among Al, Si, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb and the Bi that is selected from about 0.01～1.0 quality %.
Above-mentioned alloy is suitable for adopting Strip casting (strip cast) method for example the liquation of raw alloy is carried out chilling and to make.Below, explain and utilize the Strip casting legal system to make the quench solidification alloy.
At first, in argon atmospher, utilize high-frequency melting will have the raw alloy fusion of above-mentioned composition, form the liquation of raw alloy.Then, remain on this liquation about 1350 ℃ after, utilize the single-roller method chilling, obtain the for example sheet alloy ingot bar of the about 0.3mm of thickness.Before ensuing hydrogen is pulverized, the alloy casting piece of processing like this is ground into the for example sheet of 1～10mm size.In addition, utilize the method for Strip casting manufactured raw alloy, for example open in the specification of No. the 5383978th, United States Patent (USP).
[coarse crushing operation]
The alloy casting piece that meal is broken into above-mentioned sheet is accommodated the inside of hydrogen stove.Then, carry out hydrogen embrittlement in the inside of hydrogen stove and handle (below, be sometimes referred to as the hydrogen pulverization process) operation.When the coarse crushing alloy powder after the hydrogen pulverizing is taken out, preferably under torpescence atmosphere, take out action, so that the meal flour does not contact with atmosphere from the hydrogen stove.Like this, the oxidation of meal flour, heating can be prevented, the reduction of the magnetic characteristic of magnet can be suppressed.
Utilize hydrogen to pulverize, rare earth alloy is crushed to the size about 0.1mm～several mm, making its average grain diameter is below the 500 μ m.Preferably pulverize the back, the raw alloy of embrittlement separated carefullyyer broken, and cool off at hydrogen.When taking-up is keeping the raw material of higher temperature state, also the time of cooling processing can be prolonged relatively.
[the broken operation of micro mist]
Then, it is broken to use the jet mill reducing mechanism that the meal flour is carried out micro mist.The jet mill reducing mechanism that uses in this execution mode is connected with cyclosizer.The jet mill reducing mechanism is received in the coarse crushing operation by the supply of the rare earth alloy after the coarse crushing (meal flour), in pulverizer, pulverizes.In pulverizer,,, be collected in the recycling can through cyclosizer by the powder after pulverizing.Like this, can access the micropowder that (typically is 3～5 μ m) about 0.1～20 μ m.Being used for fine reducing mechanism like this, being not limited to jet mill, also can be ア ト ラ イ タ (a kind of high-octane ball mill) or ball mill.When pulverizing, can use lubricant such as zinc stearate as grinding aid.
[press molding]
In this execution mode, in for example Rocking Mixer (rocking mixer), in the Magnaglo of making by said method, add, mix the for example lubricant of 0.3 quality %, the with lubricator surface of clad alloy powder particle.Then, use known pressue device, in alignment magnetic field, the Magnaglo of being made by said method is shaped.The intensity in the magnetic field that applies for example is 1.5～1.7 teslas (T).In addition, forming pressure is set to the green density (green density) that makes formed body and reaches for example 4～4.5g/cm 3About.
[sintering circuit]
Preferably above-mentioned powder compact is carried out following operation successively: keep 10～240 minutes operation under the temperature in 650～1000 ℃ scope; After this under the temperature higher (for example 1000～1200 ℃), further carry out the operation of sintering than above-mentioned maintenance temperature.When sintering, particularly in Generation Liquid phase time (temperature in 650～1000 ℃ scope time), the rich R of crystal boundary in mutually begins fusion mutually, forms liquid phase.After this, carry out sintering, form sintered magnet.As stated, even, therefore after sintering circuit, also can carry out Ageing Treatment (400 ℃～700 ℃) or be used to regulate the grinding of size owing under the oxidized state in sintered magnet surface, also can implement the vapor deposition DIFFUSION TREATMENT.
[vapor deposition diffusing procedure]
Then, make heavy rare earth dvielement RH, improve coercive force H efficiently to the sintered magnet scattering and permeating of making as stated CJParticularly, in process chamber as shown in Figure 1, configuration contains RH volumes and the sintered magnet of heavy rare earth dvielement RH, through heating, from the RH volumes heavy rare earth dvielement RH is supplied to the surface of sintered magnet, simultaneously to the diffusion inside of sintered magnet.
In the diffusing procedure of this execution mode, it is identical or on this that the temperature of sintered magnet is preferably temperature with volumes.Wherein, the identical temperature difference that is meant both with the volumes temperature of the temperature of sintered magnet is in 20 ℃.Particularly, preferably the temperature with the RH volumes is set in the scope more than 700 ℃, below 1000 ℃, and the temperature of sintered magnet is set in the scope more than 700 ℃, below 1000 ℃.In addition, the interval of sintered magnet and RH volumes is set at 0.1mm～300mm as stated, is preferably 3mm～100mm, more preferably 4mm～50mm.
In addition, if the pressure of the atmosphere gas during the vapor deposition diffusing procedure is 10 -5During～500Pa, the gasification (distillation) of RH volumes is suitably carried out, carried out the vapor deposition DIFFUSION TREATMENT.In order to carry out the vapor deposition DIFFUSION TREATMENT efficiently, the pressure of atmosphere gas preferably sets 10 -3In the scope of～1Pa.In addition, the temperature of RH volumes and sintered magnet is remained on the time in the scope more than 700 ℃, below 1000 ℃, preferably set scope at 10 minutes～600 minutes.Wherein, the retention time temperature that is meant RH volumes and sintered magnet more than 700 ℃, below 1000 ℃ and pressure 10 -5Pa is above, the time below the 500Pa, is not that only expression must keep specific temperature, the time of pressure.
The diffusing procedure of this execution mode is insensitive to the surface appearance of sintered magnet, also can before diffusing procedure, form the film that is made up of Al, Zn or Sn on the surface of sintered magnet.Al, Zn and Sn are low-melting-point metal, and if amount is few can not make the magnet deterioration in characteristics, can not become the obstruction of above-mentioned diffusion in addition yet.In addition, volumes not necessarily must be made up of a kind of element, also can contain the alloy of heavy rare earth dvielement RH and element X (be selected among Nd, Pr, La, Ce, Al, Zn, Sn, Cu, Co, Fe, Ag and the In at least a).Such element X has reduced the fusing point of crystal boundary phase, is expected to reach the effect of the crystal boundary diffusion that promotes heavy rare earth dvielement RH.Through under the state that such alloy volumes and Nd sintered magnet are disposed with interval, implementing vacuum heat; Can be on magnet surface with heavy rare earth dvielement RH and element X vapor deposition, simultaneously can be preferentially via the crystal boundary phase (rich Nd phase) of formation liquid phase to the magnet diffusion inside.
In addition, when the heat treatment that is used to spread, owing to Nd, the gasification of Pr trace of crystal boundary phase, element X is so long as Nd and/or Pr just can replenish the Nd and/or the Pr of evaporation, so preferred.
After the DIFFUSION TREATMENT, also can carry out the above-mentioned heat treatment (700 ℃～1000 ℃) of appending.In addition, carry out Ageing Treatment (400 ℃～700 ℃) as required, when appending heat treatment (700 ℃～1000 ℃), after this preferred Ageing Treatment is carrying out.Appending heat treatment and Ageing Treatment can carry out in same process chamber.
In practicality, preferably the sintered magnet after the vapor deposition diffusion is implemented surface treatment.Surface treatment can be known surface treatment, for example, can carry out surface treatments such as Al vapor deposition, electroplated Ni, application of resin.Before carrying out surface treatment, can also implement known pre-treatments such as blasting treatment, cartridge type processing, etch processes, mechanical grinding.In addition, also can after DIFFUSION TREATMENT, be used to regulate the grinding of size.Even through such operation, it is also almost constant that coercive force improves effect.The stock removal that is used to regulate size is 1～300 μ m, and more preferably 5～100 μ m further are preferably 10～30 μ m.
(execution mode 2)
In this execution mode; At first; The rare earth element that preparation contains more than the 25 quality %, 40 quality % are following (wherein; Heavy rare earth dvielement RH be 0.1 quality % above, below the 5.0 quality %, all the other be light rare earth dvielement RL), 0.6 quality % is above～B (boron) of 1.6 quality %, all the other alloys for Fe and inevitable impurity.Can use C (carbon) to replace a part of B, also can use other transition metal (for example Co or Ni) to replace a part of Fe (below the 50 atom %).According to various purposes, this alloy can also contain at least a interpolation element M among Al, Si, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb and the Bi that is selected from about 0.01～1.0 quality %.
Like this, in this execution mode, in raw alloy, add more than the 0.1 quality % in advance, the heavy rare earth dvielement RH below the 5.0 quality %.Promptly; Preparing to contain light rare earth dvielement RL (among Nd and the Pr at least a) as rare earth element R and after containing the known R-Fe-B based rare earth sintered magnet of the heavy rare earth dvielement RH more than the 0.1 quality %, below the 5.0 quality %; Through the vapor deposition diffusion, make heavy rare earth dvielement RH inner from the diffusion into the surface to magnet again.
In this execution mode, carry out vapor deposition diffusion R-Fe-B based rare earth sintered magnet before, have and contain the R of light rare earth dvielement RL as main rare earth element R 2Fe 14Type B compound phase crystal grain is as principal phase, and contains that 0.1 quality % is above, the heavy rare earth dvielement RH below the 5.0 quality %.This heavy rare earth dvielement RH all exists in mutually arbitrary in mutually of principal phase and crystal boundary, therefore with in the raw alloy compares when not adding heavy rare earth dvielement RH, and the concentration difference of the heavy rare earth dvielement RH on the sintered magnet surface during the vapor deposition diffusion reduces relatively.Intracrystalline diffusion in principal phase is closely related with this concentration difference, can suppress the intracrystalline diffusion to principal phase.Consequently, crystal boundary diffusion is preferentially carried out, even therefore reduce the quantity delivered of heavy rare earth dvielement RH to magnet surface, also can make heavy rare earth dvielement RH effectively to the diffusion inside of sintered magnet.
With respect to this, under the situation of the sintered magnet that does not add heavy rare earth dvielement RH in advance, the concentration difference of the heavy rare earth dvielement RH on surface increases relatively, therefore, is easy to the intracrystalline diffusion to principal phase takes place, and the ratio of crystal boundary diffusion is reduced.
In addition, when the sintered magnet before the vapor deposition diffusion contained the heavy rare earth dvielement RH more than the 5 quality %, the concentration difference of the heavy rare earth dvielement RH of crystal boundary phase also reduced, and the coercitive raising degree that is therefore produced by the vapor deposition diffusion reduces.Therefore, from the angle that the crystal boundary that carries out heavy rare earth dvielement RH efficiently spreads, the amount of the heavy rare earth dvielement RH that the sintered magnet before the vapor deposition diffusion contains is preferably more than the 1.5 quality %, below the 3.5 quality %.
In this execution mode; Through sintered magnet to the heavy rare earth dvielement RH that contains ormal weight; Further carry out the crystal boundary diffusion of heavy rare earth dvielement RH from the sintered magnet surface, in principal phase outline portion, can be very efficiently with RH displacement light rare earth dvielement RL.Consequently, can suppress residual magnetic flux density B rReduction, and improve coercive force H CJ
(execution mode 3)
The manufacturing approach of the R-Fe-B based rare earth sintered magnet of this execution mode is implemented the sintering circuit of R-Fe-B based rare earth sintered magnet powder compact and the diffusing procedure of heavy rare earth dvielement RH continuously in same process chamber.More specifically; At first carry out containing the formed body of light rare earth dvielement RL (among Nd and the Pr at least a), relatively be configured in the operation (A) in the process chamber with the volumes that contains heavy rare earth dvielement RH (be selected among Dy, Ho and the Tb at least a) as the R-Fe-B based rare earth ferromagnetic powder of main rare earth element R.
Then, carry out through in process chamber, carrying out sintering, making and have R 2Fe 14The Type B compound crystal grain is as the operation (B) of the R-Fe-B based rare earth sintered magnet of principal phase.Then; Carry out operation (C): through in this process chamber; Volumes and R-Fe-B based rare earth sintered magnet are heated; Heavy rare earth dvielement RH is supplied to R-Fe-B based rare earth sintered magnet surface from volumes, make heavy rare earth dvielement RH be diffused into the inside of R-Fe-B based rare earth sintered magnet simultaneously.
In this execution mode, identical except sintering, the diffusing procedure with technology in the execution mode 1, therefore, below different operations only is described.
[sintering, diffusing procedure]
With reference to Fig. 2, sintering, diffusing procedure in the execution mode 3 are described.Fig. 2 is the curve of the time variation of atmosphere temperature in the process chamber in expression sintering, the diffusing procedure and atmosphere gas pressure.Single-point line expression atmosphere gas pressure in the curve, solid line is represented atmosphere temperature.
At first, the formed body of distributed magnet powder and RH volumes in process chamber shown in Figure 16 begin decompression (operation A).At this, the formed body of ferromagnetic powder can utilize known method to be shaped with micro mist according to the rare-earth sintered magnet that known method is made and to obtain.
After ferromagnetic powder formed body and RH volumes be configured in process chamber 6,, make the temperature in the process chamber 6 rise to the set point of temperature in 1000～1200 ℃ of scopes in order to begin sintering processes.Pressure (1Pa～1 * 10 when intensification preferably makes the atmosphere gas pressure in the process chamber 6 be reduced to sintering 5Pa) carry out after.It is important that pressure during sintering maintains the higher level that can fully suppress the evaporation of RH volumes.As stated;, when the pressure of atmosphere gas is high, obviously be suppressed, therefore from the evaporation rate of RH volumes evaporation heavy rare earth dvielement RH; Even in process chamber 6; Powder compact and the coexistence of RH volumes through atmosphere gas pressure is controlled at suitable scope, also can be carried out sintering circuit under not with the state in the heavy rare earth dvielement RH importing powder compact.
Sintering circuit (process B) was carried out through maintenance under the scope of above-mentioned atmosphere pressures and temperature in 10 minutes～600 minutes.In this execution mode because will heat up the time and the atmosphere gas pressure in the process B be set in 1Pa～1 * 10 5Pa is so under the state that the evaporation of RH volumes is suppressed, sintering reaction carries out rapidly.When the atmosphere gas pressure in the process B was lower than 1Pa, heavy rare earth dvielement RH proceeded from the evaporation of RH volumes, therefore only made sintering reaction carry out very difficulty.On the other hand, the atmosphere gas pressure in process B is higher than 1 * 10 5During Pa, in the sintering process, residual in the powder compact have gas, might make residual hollow hole part in the sintered magnet.Therefore, the atmosphere gas pressure in the process B preferably sets in 1Pa～1 * 10 5The scope of Pa more preferably is set in 5 * 10 2Pa～10 4The scope of Pa.
After sintering circuit (process B) finishes, the atmosphere temperature of process chamber 6 is reduced to 800～950 ℃ of (process B 1').Then, atmosphere gas pressure is decompressed to 1 * 10 -5Pa～1Pa (process B 2').The temperature that is suitable for the diffusion of heavy rare earth dvielement RH is 800～950 ℃, is being reduced to the process (process B of this temperature range 1') in, preferably suppress the evaporation of RH volumes.In this execution mode, atmosphere temperature is being reduced to after 800～950 ℃ the reduction (process B of beginning atmosphere pressures 2').Therefore, after dropping to the temperature that is suitable for the vapor deposition diffusion, the evaporation of beginning RH volumes can be implemented diffusing procedure C efficiently.
In diffusing procedure C, atmosphere gas pressure is remained on 1 * 10 -5Pa～1Pa, chamber temperature remain on 800～950 ℃, carry out above-mentioned vapor deposition diffusion.In diffusing procedure C, through the vapor deposition diffusion, the crystal boundary diffusion is preferential to be taken place, and therefore can suppress the formation of intracrystalline diffusion layer, suppresses residual magnetic flux density B rReduction.
The curve chart that Fig. 3 changes for the expression pressure and temp different with execution mode shown in Figure 2.In example shown in Figure 3, at sintering circuit B not between tailend, reduce atmosphere gas pressure (process B " 1).Then, be 1 * 10 at atmosphere gas pressure -5Temperature in the Pa～1Pa, process chamber be 1000～1200 ℃ carry out down 10～300 minutes heat treatments (process B " 2) after, with the temperature of process chamber 6 reduce to 800～950 ℃ (process B " 3).In the example of Fig. 3,, therefore can shorten the total time of total operation owing in the way of sintering circuit B, begin the evaporation of RH volumes.
In addition, carrying out intensification before the sintering circuit does not need like Fig. 2, shown in Figure 3ly carries out according to certain speed, can be in the way of heating up, for example append under the temperature in 650～1000 ℃ scope, and keep 10～240 minutes operation.
In addition, the diffusing procedure of this execution mode is insensitive to the surface appearance of sintered magnet, also can before diffusing procedure, form the film that is made up of Al, Zn or Sn on the sintered magnet surface.Al, Zn or Sn are low-melting-point metal, and if amount is few can not make the magnet deterioration in characteristics, in addition, can not become the obstruction of above-mentioned diffusion yet.In the RH volumes, also can contain elements such as Al, Zn or Sn.
Can know by above-mentioned explanation; In this execution mode; Need not change existing technology significantly,, just can heavy rare earth dvielement RH be supplied to the depth location of sintered magnet inside through carrying out the crystal boundary diffusion of heavy rare earth dvielement RH (be selected among Dy, Ho and the Tb at least a); At the principal phase housing department, can be efficiently with heavy rare earth dvielement RH displacement light rare earth dvielement RL.Its result can suppress residual magnetic flux density B rReduction, improve coercive force H simultaneously CJ
Embodiment
Embodiment 1
At first, use, adopt the alloy sheet of the thick 0.2～0.3mm of Strip casting manufactured to have Nd:31.8, B:0.97, Co:0.92, Cu:0.1, Al:0.24, alloy that all the other cooperate as the mode of the composition of Fe (quality %).
Then, this alloy sheet is filled in the container, is housed in the hydrogen treating device.Then, through making the hydrogen atmosphere that is full of pressure 500kPa in the hydrogen treating device, at room temperature, discharge after making the alloy sheet absorbing hydrogen.Through implementing such hydrogenation treatment, make the alloy sheet embrittlement, make the amorphous powder of the about 0.15～0.2mm of size.
After adding the zinc stearate of mixing, carry out the pulverizing process of jet mill device, the attritive powder of the about 3 μ m of the particle diameter that makes powder as the 0.05wt% of grinding aid to the coarse crushing powder of making by above-mentioned hydrogenation treatment.
Utilize molding device to be shaped the attritive powder of making like this, make powder compact.Particularly, in externally-applied magnetic field,, implement die forming at magnetic field orientating state lower compression powder particle.Then, from molding device, take out formed body, utilize vacuum furnace, under 1020 ℃, carry out 4 hours sintering circuit.Like this, after making the sintering blocks, this sintering blocks is carried out machining, obtain the sintered magnet of thick 1mm * long 10mm * wide 10mm.
After this sintered magnet carried out pickling and drying with 0.3% aqueous solution of nitric acid, be configured in the container handling with structure shown in Figure 1.The container handling that present embodiment uses is formed by Mo, possesses the parts and the parts that keep two RH volumes of a plurality of sintered magnets of supporting.The interval of sintered magnet and RH volumes is set in about 5～9mm.The RH volumes is formed by the Dy of purity 99.9%, has the size of 30mm * 30mm * 5mm.
Then, the container handling with Fig. 1 heats enforcement heat treatment in vacuum heat treatment furnace.Heat treated condition is shown in below table 1.In addition, as long as hereinafter do not have special declaration, heat treatment temperature is meant the temperature of sintered magnet and almost equal with it RH volumes.
Table 1
Figure G2009101592585D00231
After the enforcement of the condition shown in the table 1 heat treatment, implement Ageing Treatment (pressure 2Pa, 500 ℃ following 60 minutes).
In addition, the surface by utilizing cartridge type electron ray heating vapour deposition method (power 16kW, 30 minutes) of also preparing sintered magnet is coated with the sample of Al (thickness 1 μ m), heat-treats according to the condition X shown in the table 1, Y.After the heat treatment, implement Ageing Treatment (pressure 2Pa, 500 ℃ following 60 minutes).
For each sample, behind the impulse magnetization of implementing 3MA/m, show mark device (tracer) mensuration magnet characteristic (residual magnetic flux density: B with B-H r, coercive force: H CJ).In addition, utilize EPMA (the system EPM-810 of Shimadzu Seisakusho Ltd.) to estimate Dy to the inner diffusion-condition of magnet.The residual magnetic flux density B that obtains by mensuration rWith coercive force H CJShown in following table 2.
Table 2
Sample The Al overlay film Heat-treat condition B r[T] H cJ[kA/m]
1 Do not have There is not diffusion * 1.40 850
2 Do not have X 1.40 1211
3 Have X 1.39 1228
4 Do not have Y 1.39 1402
5 Have Y 1.38 1422
6 Do not have Z 1.37 1601
In the comparative example of sample 1, do not implement the vapor deposition DIFFUSION TREATMENT of Dy, with the same heat-treat condition of sample 2～6 under implement Ageing Treatment.Can know that by table 2 sample 2～6 of implementing the Dy diffusion of the present invention is compared with comparative example (sample 1), has increased substantially coercive force H CJCan know that in addition even implementing diffusion is formed with Al film (thickness 1 μ m) before on the sintered magnet surface sample 3,4, the existence of Al film does not have to constitute especially the obstacle of Dy diffusion yet, can improve coercive force H yet CJ
Fig. 4 and Fig. 5 represent the photo of the cross section EPMA analysis result that sample 2 and sample 4 obtain respectively.Fig. 4 (a) and (b), (c), (d) represent the reflection photo of the distribution of BEI (reflection electronic ray image), Nd, Fe and Dy respectively.Fig. 5 too, the face on the top in each photo is equivalent to the surface of sintered magnet.
In the photo of Fig. 4 (d) and Fig. 5 (d), clearly represent the part that Dy exists with relative higher concentration.Can know that by these photos the zone that Dy exists with higher relatively concentration is near the crystal boundary.Even near the part magnet surface, Dy is few with the zone that near the concentration that is equal extent principal phase central portion and the crystal boundary spreads.The Dy film is deposited in the sintered magnet surface, by the method for this Dy film to the sintered magnet diffusion inside, in sintered magnet near surface zone, observes the principal phase that Dy is arranged with the high concentration diffusion in a large number according to Dy.
According to the present invention, regional from the sintered magnet surface to the top layer that reaches 100 μ m deeply, principal phase (Nd 2Fe 14The Type B compound crystal grain) central portion does not have the Dy diffusion, and near the Dy concentration the Dy concentration ratio crystal boundary of principal phase central portion is low.This means that in the zone, above-mentioned top layer, before the intracrystalline diffusion was carried out, Dy was diffused into sintered magnet inside mutually through crystal boundary.Therefore, can access residual magnetic flux density B rAlmost do not reduce coercive force H CJThe rare-earth sintered magnet that improves.
Fig. 6 representes the mensuration result of Dy concentration of principal phase central portion and the crystal boundary triple point of sample 2,3.At this, the principal phase central portion in the sample 2 and the Dy concentration of crystal boundary triple point are used " ◆ " and " ◇ " expression respectively, and the principal phase central portion in the sample 3 and the Dy concentration of crystal boundary triple point are used " ● " and " zero " expression respectively.
Be positioned at apart from the zone of the degree of depth of surperficial about 50 μ m of sintered magnet, the Dy concentration of principal phase central portion is extremely low, otherwise the Dy concentration of crystal boundary triple point obviously rises.On the other hand, be positioned at apart from the zone of the degree of depth of surperficial about 500 μ m of sintered magnet, any one sample all almost can not detect Dy.
Fig. 7 representes the mensuration result of Dy concentration of principal phase central portion and the crystal boundary triple point of sample 4,5.For the principal phase central portion of sample 4,5, the position that Dy concentration is the highest is designated as α, and the position that Dy concentration is minimum is designated as β.The Dy concentration of principal phase central portion α, principal phase central portion β and the crystal boundary triple point of sample 4 is used " ◆ ", " △ " and " ◇ " expression respectively; On the other hand, the Dy concentration of principal phase central portion α, principal phase central portion β and the crystal boundary triple point of sample 5 is used " ● ", " " and " zero " expression respectively.
According to The above results, in arbitrary sample, between principal phase central portion and the crystal boundary phase, Dy concentration all produces the above difference of 2mol% (=2 atom %).
Embodiment 2
Preparation is according to the sintered magnet made from the illustrated same method of method of embodiment 1.Be of a size of 7mm * 7mm * 3mm.The direction of magnetization is set on the direction of thickness 3mm.After above-mentioned sintered magnet carried out pickling and drying with 0.3% nitric acid, as shown in Figure 1, with Dy plate (30mm * 30mm * 5mm, 99.9%) configuration relatively.
Then, the container handling of Fig. 1 is heated in vacuum heat treatment furnace, implement heat treatment according to the condition shown in the table 3 after, implement Ageing Treatment (pressure 2Pa, 500 ℃ are following 60 minutes).
Table 3
Figure G2009101592585D00251
In addition, will not implement DIFFUSION TREATMENT, according to the comparative example of having implemented Ageing Treatment with embodiment 2 same conditions as sample 7.After Ageing Treatment, show mark device mensuration magnet characteristic (residual magnetic flux density B with B-H r, coercive force H CJ).Measure the result shown in below table 4.
Table 4
Sample B r[T] H cJ[kA/m]
7 1.42 911
8 1.42 923
9 1.42 943
10 1.42 1079
11 1.42 1112
12 1.40 1352
13 1.40 1298
14 1.42 1143
15 1.42 1100
16 1.42 909
Can know by these results, in the present embodiment, even the thickness of sintered magnet is 3mm, residual magnetic flux density B rAlmost do not reduce coercive force H CJIncrease substantially.
Fig. 8 (a) and (b) be to represent treatment temperature and residual magnetic flux density B respectively r, coercive force H CJThe curve chart of relation.Can know coercive force H by these curves CJAlong with treatment temperature (pressure: 1 * 10 -2Pa, time: 30 minutes) increase and increasing.In curve, " through overpickling " is meant with behind the clean sintered magnet surface of 0.3% nitric acid, do not form the sample of overlay film on the surface, and " Al coating " is meant on the sintered magnet surface, utilizes electron ray heating vapour deposition method to pile up the sample that the Al film is arranged.
Fig. 9 (a) and (b) be to represent processing time and residual magnetic flux density B respectively r, coercive force H CJThe curve chart of relation.Can know coercive force H by these curves CJAlong with processing time (pressure: 1 * 10 -2Pa, temperature: 900 ℃) increase and increasing.In curve, " through overpickling " and " Al coating " as stated, " through cut off " is meant the goods that utilize after diamond cutter cuts off.
Figure 10 (a) and (b) be pressure and the residual magnetic flux density B that representes respectively in the container handling r, coercive force H CJThe curve chart of relation.The transverse axis of curve is represented the pressure of the argon gas atmosphere in the container handling.Can be known by Figure 10 (b), be 1 * 10 at pressure 2Under the situation below the Pa, coercive force H CJExist with ... pressure hardly.At pressure is 1 * 10 5Under the situation of Pa (atmospheric pressure), can not obtain coercive force H CJThe raising effect.EPMA analysis by magnet surface can know that when the pressure in the container handling was atmospheric pressure, Dy did not have vapor deposition, diffusion.According to this result, when the pressure of handling atmosphere is enough high, even heating Dy plate, also might make Dy not vapor deposition, be diffused in the adjacent sintered magnet.So,, just can in same process chamber, implement sintering circuit and Dy vapor deposition, diffusing procedure successively through controlled atmospher pressure.That is, can when implementing sintering circuit, make atmosphere pressures enough high, under the state that suppresses vapor deposition, diffusion, carry out sintering from the Dy of Dy plate.Then, after sintering finishes, can reduce, supply with Dy and diffusion to sintered magnet by the Dy plate through making atmosphere pressures.As long as the sintering circuit of making and Dy diffusing procedure can be implemented like this, just can reduce manufacturing cost in same device.
Embodiment 3
In the present embodiment, research Dy separates out and handles the relation of the pressure (vacuum degree) of atmosphere.In the present embodiment, (the Mo package body: Mo pack), portion is provided with Dy plate (30mm * 30mm * 5mm, 99.9%) within it to use Mo container made shown in Figure 11.The inwall of Mo package body is pasted with the Nb paper tinsel.In vacuum heat treatment furnace, accommodate the Mo package body of Figure 11,900 ℃ of heat treatments of implementing 180 minutes down.Pressure (vacuum degree) in the vacuum heat treatment furnace gets (1) 1 * 10 -2Three conditions of Pa, (2) 1Pa, (3) 150Pa.
Figure 12 is the photo of the outward appearance observed result of the Mo package body inwall after the expression heat treatment.The part of variable color is that Dy separates out the zone on the internal face of Mo package body.Under the vacuum degree of (1), Dy evenly is deposited on the whole inwall of Mo package body.Under the vacuum degree of (2), only near the Dy plate, produce Dy and pile up.Under the vacuum degree of (3), the Dy evaporation capacity tails off, and the area of Dy build-up areas also dwindles.In addition, in the variable color part, Dy is not almost by film forming, and supposition is that temporary transient variable color Dy partly attached to inwall gasifies once more.Through the vacuum degree of such adjusting heat-treating atmosphere, just can control the evaporation rate (amount) of Dy and separate out the zone.
Embodiment 4
Will be according to sintered magnet and shown in figure 13 being configured of Dy plate (30mm * 30mm * 5mm, 99.9%) made from the illustrated same method of method of embodiment 1, in vacuum heat treatment furnace, 900 ℃ of heat treatments of 120 minutes of enforcement down.Vacuum degree is set at (1) 1 * 10 -2Three conditions of Pa, (2) 1Pa, (3) 150Pa.
Sample A～the C of sintered magnet shown in Figure 13 has 7mm * 7mm * 3mm, and (thickness: the size direction of magnetization), only sample D has 10mm * 10mm * 1.2mm (thickness: the size direction of magnetization).These sintered magnets all after carrying out pickling, drying by 0.3% nitric acid, have been implemented heat treatment.
After further under 500 ℃, 60 minutes, the condition of vacuum degree 2Pa, carrying out Ageing Treatment, use BH to show that the mark device measures magnet characteristic (residual magnetic flux density: B r, coercive force: H CJ).The mensuration result of data such as table 5 is illustrated under vacuum degree (1)～(3), the weight relevant with Sample A～D and magnet characteristic.
Table 5
Figure G2009101592585D00281
Can know that by table 5 characteristic of sintered magnet A～D is not improved with almost having deviation.In addition, try to achieve the Dy rate of finished products by the weight change before and after the heat treatment shown in the table 5.Wherein, the Dy rate of finished products is with the expression of (being processed the Dy recruitment of part (sintered magnet, Nb paper tinsel))/(Dy plate reduction) * 100.Along with the reduction of vacuum degree, the Dy rate of finished products improves, and under the vacuum degree of (3), is about 83%.In addition, under all vacuum degree ((1)～(3)), compare the weight increase of Nb paper tinsel (per unit area) with sintered magnet) all especially little.This shows that the Nb surface do not react (alloying) with Dy flies Dy surperficial to Nb and that separate out and evaporates once again, the Dy film forming on the Nb paper tinsel is not worked.In other words,,, improved the Dy rate of finished products, very big contribution has been arranged saving resource so compare with other known method of diffusion owing on sintered magnet, also spread from the preferential vapor deposition of Dy of Dy plate evaporation.
Embodiment 5
Will be according to the sintered magnet and shown in figure 14 being configured of Dy plate (20mm * 30mm * 5mm, 99.9%) made from the illustrated same method of method of embodiment 1, at 900 ℃, 1 * 10 -2Implement heat treatment under the condition of Pa.At this moment, as shown in table 6, the distance of change magnet and Dy plate.Sintered magnet is 7mm * 7mm * 3mm (thickness: the direction of magnetization), carry out pickling, drying with 0.3% nitric acid.After the heat treatment, under 500 ℃, 60 minutes, the condition of 2Pa, carry out Ageing Treatment after, use BH to show that the mark device measures magnet characteristic (residual magnetic flux density: B r, coercive force: H CJ).
Table 6
Figure G2009101592585D00291
Like table 7, shown in Figure 15, according to the distance of sintered magnet and Dy plate, coercitive raising degree changes to some extent.Reach till the 30mm to distance, raisings degree does not reduce yet, but distance is again when becoming big, the minimizing of raising degree.But, even distance more than 30mm, through prolonging heat treatment time, can improve coercive force.
Table 7
B r[T] H cJ[kA/m] B r[T] H cJ[kA/m]
Element material 1.42 911 ④ 1.41 1289
① 1.42 1096 ⑤ 1.42 1255
② 1.42 1102 ⑥ 1.42 1010
③ 1.42 1033
Embodiment 6
To use vacuum heat treatment furnace, at 900 ℃, 1 * 10 according to the sintered magnet and shown in figure 16 being configured of Dy plate (30mm * 30mm * 5mm, 99.9%) made from the illustrated same method of method of embodiment 1 -2Implement heat treatment under the condition of Pa.At this moment, dispose up and down, only be configured at the Dy plate above, only implement heat treatment under the situation below being configured in.Sintered magnet has 7mm * 7mm * 3mm, and (thickness: the size direction of magnetization), it is also dry to carry out pickling with 0.3% nitric acid.
After under 500 ℃, 60 minutes, the condition of 2Pa, carrying out Ageing Treatment, use BH to show that the mark device measures magnet characteristic (residual magnetic flux density: B r, coercive force: H CJ).Figure 17 representes the mensuration result of magnet characteristic.
Shown in figure 17, with the configuration-independent of Dy plate, coercive force all improves.Think that this is because when vacuum treatment, the Dy of gasification evenly is present in the near surface of sintered magnet.
The EPMA analysis result on the sintered magnet surface after the heat treatment when Figure 18 representes that the Dy plate only is configured under the sintered magnet.Figure 18 (a) is the photo of analysis result of the upper central portion of expression sintered magnet, (b) is the photo of the analysis result of the following central portion of expression sintered magnet.Hence one can see that, the upper central portion of sintered magnet also with following central portion almost vapor deposition, diffusion likewise Dy arranged.The Dy that this means evaporation evenly distributes at the sintered magnet near surface.
Embodiment 7
To the condition X of embodiment 1 (the 900 ℃ * sample of having implemented the vapor deposition DIFFUSION TREATMENT under 30min) implement the test of moisture-proof lubricant nature (80 ℃, 90%RH).Figure 19 is the photo of the situation of getting rusty of the magnet surface after the test of expression moisture-proof lubricant nature; " through overpickling " be meant with 0.3% nitric acid with sintered magnet pickling drying after, do not carry out the vapor deposition DIFFUSION TREATMENT, implement Ageing Treatment (pressure 2Pa; 500 ℃ 60 minutes) situation; " 1-A " be with " through overpickling " similarity condition under implement pickling after, under the condition X of embodiment 1, implement the situation of vapor deposition DIFFUSION TREATMENT and Ageing Treatment, " 1-B " be with " through overpickling " similarity condition under after the enforcement pickling; Under the condition identical, implement Al and apply, the situation of enforcement vapor deposition DIFFUSION TREATMENT and Ageing Treatment under the condition X of embodiment 1 with embodiment 1.No matter can be known by Figure 19, compare with the sample of " through overpickling ", be " 1-A " or " 1-B ", and the moisture-proof lubricant nature all improves.Think this be because, implemented DIFFUSION TREATMENT of the present invention after, formed the fine and close mixed phase tissue of Dy or Nd, the uniformity of current potential improves, consequently, potential difference is corroded and is difficult to carry out.
Embodiment 8
The Nd sintered magnet of the composition (Dy 0% forms) of the 31.8Nd-bal.Fe-0.97B-0.92Co-0.1Cu-0.24Al (quality %) that will make with the condition of embodiment 1 is cut out and is processed into 10mm * 10mm * 3mm (direction of magnetization).Configuration shown in figure 20 is implemented 900 ℃, 1 * 10 -2Pa, 120 minutes heat treatment.Then, 500 ℃ of enforcements, 2Pa, 120 minutes Ageing Treatment.The composition of table 8 expression Dy-X alloy.
Table 8
Dy-Nd is because be solid fully fusion gold, so the composition ratio of Dy and Nd is 50: 50 (quality %).For other alloy, select Dy to become the composition ratio of cocrystalization compound with X-shaped.
To the sample before and after the vapor deposition diffusion, show mark device mensuration magnet characteristic (residual magnetic flux density B with B-H r, coercive force H CJ).Figure 21 (a) and (b) with (c) be expression residual magnetic flux density B respectively r, coercive force H CJAnd squareness ratio (H k/ H CJ) curve chart.
Curve by Figure 21 (b) can be known, the coercive force H of all samples CJAll improve.This is because through spreading to the inner Dy of sintered magnet, at principal phase (Nd 2Fe 14The B crystallization) housing department forms high denseization of the Dy layer of anisotropy field.Dy-X for beyond the Dy-Al compares with the situation that singly contains Dy, and coercive force raising degree is equal, but has suppressed residual magnetic flux density and squareness ratio (H k/ H CJ) reduction.This is inferred to be, because through not only making Dy, and makes the also vapor deposition diffusion of X element, can reduce the fusing point of crystal boundary phase, so further promoted the diffusion of Dy.This effect is very remarkable when containing Nd as element X.Think that this is because volumes is supplied with sintered magnet with Nd, thus when heat treatment, can fill up the rare earth element (Nd, Pr) of the trace that evaporates mutually from the crystal boundary of sintered magnet.
In addition, confirm that according to method same as described above, the element (La, Ce, Cu, Co, Ag, Zn, Sn) beyond the X element of table 8 also has same effect.
Embodiment 9
To cut out processing according to the sintered magnet made from the illustrated same method of method of embodiment 1, obtain the sintered magnet of 6mm (direction of magnetization) * 6mm * 6mm.This sintered magnet and Dy plate dispose shown in Figure 22 (a).Particularly, at the Dy of configuration up and down of sintered magnet plate, the mode that is approximately perpendicular to the opposite face of Dy plate up and down with the direction of magnetization of sintered magnet is configured.Remain under this state, in vacuum heat treatment furnace, at 900 ℃, 1 * 10 -2Under the condition of Pa, implement 120,240,600 minutes heat treatment respectively.Then, implement 500 ℃, 2Pa, 120 minutes Ageing Treatment.
Figure 22 (b) is the figure of the crystal orientation of expression sintered magnet.In Figure 22 (b), have cubic shaped the surface of sintered magnet in, be expressed as " aa face " perpendicular to the face of c axle (direction of magnetization), the face that is not orthogonal to the c axle is expressed as " ac face ".
When above-mentioned heat treatment, in sample aa2, only expose two " aa faces " in six of sintered magnet, other four faces cover with the Nb paper tinsel of thickness 0.05mm.Equally, in sample ac2, only expose two " ac faces ", other four faces cover with the Nb paper tinsel of thickness 0.05mm.
Sample before and after the above-mentioned heat treatment is shown mark device mensuration magnet characteristic (residual magnetic flux density B with B-H r, coercive force H CJ).
Figure 23 is expression coercive force H CJRecruitment and residual magnetic flux density B rThe curve chart of reduction amount.When heat treatment time more than 240 minutes the time, the residual magnetic flux density B of sample aa and sample ac rThe reduction amount be equal extent, but sample aa compares coercive force H with sample ac CJThe big 100kA/m of recruitment about.
Then, in order to study the diffusion length of Dy, use the sample of handling 240 minutes,, utilize B-H to show the mark device mensuration magnet characteristic during 0.2mm under the grinding of surface whenever sample aa2 and sample ac2.
The coercive force H that Figure 24 records for expression as stated CJCurve chart.In sample ac2, when total grinds away about 0.6mm, coercive force H CJWith value before the heat treatment about equally.On the other hand, in sample aa, when total grinds away about 1.2mm, coercive force H CJWith value before the heat treatment about equally.From the above, the diffusion velocity of c direction of principal axis (direction of orientation) reaches about 2 times of diffusion velocity of perpendicular direction.
Embodiment 10
Will be according to the sintered magnet of the size of thick 3mm (the direction of magnetization) * long 25mm * wide 25mm that makes with the illustrated same method of method of embodiment 1, shown in Figure 25 (a), with about 50% of the surface of Nb paper tinsel covering sintered magnet.Then, as shown in Figure 1 being configured is in vacuum heat treatment furnace, at 900 ℃, 1 * 10 -2Under the condition of Pa, implement 120 minutes heat treatment.Then, implement 500 ℃, 2Pa, 120 minutes Ageing Treatment.After the heat treatment, attached to the Dy on the Nb paper tinsel seldom, and do not react also welding and on sintered magnet, can easily peel off with sintered magnet.
To the sample after the above-mentioned heat treatment,, determine the part of size with diamond cutter with thick 3mm (direction of magnetization) * long 7mm * wide 7mm from position shown in Figure 25 (b).Then, show that with B-H the mark device measures that scattering and permeating has the part (sample E) of Dy and magnet characteristic (the residual magnetic flux density B of the part (sample F) that coated by the Nb paper tinsel r, coercive force H CJ).
Measure the result shown in below table 9.Confirm to coat, and scattering and permeating there is the part of Dy, compares coercive force H with the part that coats by the Nb paper tinsel by the Nb paper tinsel CJBe improved.Like this, according to present embodiment, with respect to the specific part of sintered magnet, optionally spread Dy, the magnet characteristic of this part other part relatively changes.
Table 9
Sample B r[T] H cJ[kA/m]
E 1.40 1254
F 1.42 870
Embodiment 11
At first, use with 5 kinds of composition with table 10 (the alloy ingot bar that the mode of L～P) cooperates, through the Strip casting method, the alloy sheet of making thickness 0.2～0.3mm.
Then, this alloy sheet is filled in the container, is housed in the hydrogen treating device.Then through making the hydrogen atmosphere that is full of pressure 500kPa in the hydrogen treating device, at room temperature, discharge after making the alloy sheet absorbing hydrogen.Through implementing such hydrogenation treatment, make the alloy sheet embrittlement, make the amorphous powder of the about 0.15～0.2mm of size.
After adding the zinc stearate of mixing, carry out the pulverizing process of jet mill device, the attritive powder of the about 3 μ m of the particle diameter that makes powder as the 0.05wt% of grinding aid to the coarse crushing powder of making by above-mentioned hydrogenation treatment.
Utilize molding device to be shaped the attritive powder of making like this, make powder compact.Particularly, in externally-applied magnetic field,, implement die forming at magnetic field orientating state lower compression powder particle.Then, from molding device, take out formed body, utilize vacuum furnace, under 1020 ℃, carry out 4 hours sintering circuit.Like this, after making the sintering blocks, this sintering blocks is carried out machining, obtain the sintered magnet of the size of table 11.
Table 10
(quality %)
Figure G2009101592585D00341
Table 11
Figure G2009101592585D00342
After this sintered magnet carried out pickling and drying with 0.3% aqueous solution of nitric acid, be configured in the container handling with structure shown in Figure 1.The container handling that present embodiment uses is formed by Mo, possesses the parts and the parts that keep two RH volumes of a plurality of sintered magnets of supporting.The interval of sintered magnet and RH volumes is set in about 5～9mm.The RH volumes is formed by the Dy plate of purity 99.9%, has the size of 30mm * 30mm * 5mm.
Then, the container handling of Fig. 1 is heated in vacuum heat treatment furnace, implement to be used for the heat treatment of vapor deposition diffusion.Heat treated condition is as shown in table 11.In addition, short of special declaration, heat treatment temperature is meant the temperature of sintered magnet and almost equal with it RH volumes.
After the diffusion of the enforcement of condition shown in the table 11 vapor deposition, implement Ageing Treatment (pressure 2Pa, 500 ℃ following 60 minutes).
To before the vapor deposition diffusion with Ageing Treatment after each sample, behind the impulse magnetization of implementing 3MA/m, show that with B-H the mark device measures magnet characteristic (coercive force: H CJ, residual magnetic flux density: B r).Measure according to this, calculate with respect to implement the coercive force H of the preceding sample of vapor deposition diffusion CJWith residual magnetic flux density B r, because of the variable quantity of vapor deposition diffusion (Ageing Treatment) generation.
Figure 26 (a) forms the coercive force variation delta H of L～P for expression CJCurve chart.◇ in the curve,, ◆ represent to implement the coercive force variation delta H of the sample of vapor deposition diffusion respectively with the data point of ■ with the condition of the α in the table 11, β, γ and δ CJ
On the other hand, Figure 26 (b) forms the residual magnetic flux density variation delta B of L～P for expression rCurve chart.◇ in the curve,, ◆ represent to implement the residual magnetic flux density variation delta B of the sample of vapor deposition diffusion respectively with the data point of ■ with the condition of the α in the table 11, β, γ and δ r
Can know by Figure 26 (a) and (b), form in the sintered magnet of B (Dy 2.5%), can suppress residual magnetic flux density B rReduction the time, obtain the highest coercive force H CJ
After grind in the sample enforcement cross section of sample before the vapor deposition diffusion of his-and-hers watches 11 and vapor deposition diffusion back (after the Ageing Treatment), utilize EPMA (the system EPM-1610 of Shimadzu Seisakusho Ltd.) to analyze (ZAF method).The Dy amount (quality %) of following table 12 expression principal phase central portions and crystal boundary triple point portion.
Table 12
It is as shown in table 12 that the sample of forming M can obtain the reason of excellent magnet characteristic, can infer that this is because in having the sample of forming M, can carry out spreading mutually to the Dy of crystal boundary with peak efficiency.
Embodiment 12
At first, use, adopt the alloy sheet of the thick 0.2～0.3mm of Strip casting manufactured to have Nd:31.8, B:0.97, Co:0.92, Cu:0.1, Al:0.24, alloy ingot bar that all the other cooperate as the mode of the composition of Fe (quality %).
Then, this alloy sheet is filled in the container, is housed in the hydrogen treating device.Then, through making the hydrogen atmosphere that is full of pressure 500kPa in the hydrogen treating device, at room temperature, discharge after making the alloy sheet absorbing hydrogen.Through implementing such hydrogenation treatment, make the alloy sheet embrittlement, make the amorphous powder of the about 0.15～0.2mm of size.
After adding the zinc stearate of mixing, carry out the pulverizing process of jet mill device, the attritive powder of the about 3 μ m of the particle diameter that makes powder as the 0.05wt% of grinding aid to the coarse crushing powder of making by above-mentioned hydrogenation treatment.
Utilize molding device to be shaped the attritive powder of making like this, make the powder compact of 20mm * 10mm * 5mm (magnetic direction).Particularly, in externally-applied magnetic field,, implement die forming at magnetic field orientating state lower compression powder particle.Then, from molding device, take out formed body, be configured in the container handling with structure shown in Figure 1.The container handling that present embodiment uses is formed by Mo, possesses the parts and the parts that keep two RH volumes of a plurality of formed bodies of supporting.The interval of formed body and RH volumes is set in about 5～9mm.The RH volumes is formed by the Dy plate of purity 99.9%, has the size of 30mm * 30mm * 5mm.
This container handling is housed in the vacuum furnace,, implements sintering circuit and diffusing procedure according to condition shown in the table 13.In table 1, the sintering relevant, the condition of diffusing procedure have been represented with 12 samples of " 1-A "～" 6-B "." A " of table 13 is meant as shown in Figure 1, and powder compact and Dy plate are together disposed and implement heat treated embodiment.On the other hand, the Dy plate is not disposed in " B " of table 13 expression, powder compact is implemented the heat treated comparative example of similarity condition.The whichever sample behind the diffusing procedure, is all implemented 500 ℃, 2Pa, 120 minutes Ageing Treatment.
Table 13
To each sample of gained, show mark device mensuration magnet characteristic (residual magnetic flux density B with B-H r, coercive force H CJ).
Figure 27 (a) is expression and 12 residual magnetic flux density B that sample is relevant rThe curve chart of measured value, Figure 27 (b) is the expression coercive force H relevant with said sample CJThe curve chart of measured value.
Can know the coercive force H of all embodiment (1-A, 2-A, 3-A, 4-A, 5-A, 6-A) by these figure CJThe coercive force H that is higher than comparative example (1-B, 2-B, 3-B, 4-B, 5-B, 6-B) significantly CJEspecially in sample 4-A, residual magnetic flux density B rRate of descent minimum.This shows that after accomplishing sintering under the higher relatively atmosphere pressures, when the evaporation diffusion of beginning Dy, Dy is spread by crystal boundary most effectively mutually, has effectively improved coercive force H CJ
Embodiment 13
At first, use, likewise make sintered magnet with embodiment 1 to have Nd:32.0, B:1.0, Co:0.9, Cu:0.1, Al:0.2, alloy that all the other cooperate as the mode of the composition of Fe (quality %).This sintered magnet is cut into the size of 7mm * 7mm * 3mm.
In structure shown in Figure 1, use the Tb plate as RH volumes 4, and heat-treat.Heat treatment is under 900 ℃ or 950 ℃, 1 * 10 -3Pa implemented 120 minutes down.Then, implement 500 ℃, 2Pa, 120 minutes Ageing Treatment.
Sample before and after the vapor deposition diffusion is shown mark device mensuration magnet characteristic (residual magnetic flux density B with B-H r, coercive force H CJ) time, the magnetic characteristic of the magnet before the vapor deposition diffusion is B r=1.40T, H CJ=850kA/m, the magnetic characteristic of the magnet after the vapor deposition diffusion is respectively B r=1.40T, H CJ=1250kA/m, B r=1.40T, H CJ=1311kA/m.
Can confirm by The above results, through making the diffusion of Tb vapor deposition, residual magnetic flux density B rDo not reduce, can improve coercive force H CJ
Embodiment 14
Likewise make the sample of sintered magnet with the foregoing description 13.After as shown in Figure 1 being configured, implement to spread to the vapor deposition of sintered magnet from the RH volumes 4 that constitutes by Dy.Particularly, implement 900 ℃, 1 * 10 -2The heat treatment of Pa, 60 minutes or 120 minutes.
To a part of sample, after vapor deposition diffusion, implement 500 ℃, 2Pa, 120 minutes Ageing Treatment.To all the other samples, in structure shown in Figure 1, under the state of removing RH volumes 4, implementing 900 ℃, 1 * 10 -2After Pa, 120 minutes the heat treatment, implement 500 ℃, 2Pa, 120 minutes Ageing Treatment.Then, to above-mentioned each sample, show mark device mensuration magnet characteristic with B-H.Measure the result and be shown in table 14.
Table 14
Figure G2009101592585D00381
Can know,, can further improve coercive force through implementing to append heat treatment.
Utilizability on the industry
According to the present invention, even in the inside of sintered magnet, also can efficiently form heavy rare earth dvielement RH at the principal phase crystal grain that housing department efficiently concentrates, therefore, the high-performance that has high residual magnetic flux density and high-coercive force concurrently magnet can be provided.

Claims (5)

1. diffusion processing apparatus is characterized in that having:
Process chamber;
Holding member; In said process chamber, volumes and R-Fe-B based rare earth sintered magnet are disposed relatively, wherein; Said volumes contains heavy rare earth dvielement RH, and said R-Fe-B based rare earth sintered magnet has and contains the R of light rare earth dvielement RL as main rare earth element R 2Fe 14The Type B compound crystal grain is as principal phase, and said heavy rare earth dvielement RH is selected from least a among Dy, Ho and the Tb, and said light rare earth dvielement RL is at least a among Nd and the Pr; With
Heating unit is more than 700 ℃, below 1000 ℃ with the adjustment in the said process chamber,
This diffusion processing apparatus constitutes; To reducing pressure in the said process chamber; Utilize said heating unit; Said volumes and said R-Fe-B based rare earth sintered magnet are carried out heat treated, thus heavy rare earth dvielement RH is supplied to the surface of said R-Fe-B based rare earth sintered magnet from said volumes, make said heavy rare earth dvielement RH be diffused into the inside of said R-Fe-B based rare earth sintered magnet simultaneously.
2. diffusion processing apparatus as claimed in claim 1 is characterized in that:
The internal face of said process chamber is by not forming with the material of said heavy rare earth dvielement RH reaction.
3. diffusion processing apparatus as claimed in claim 2 is characterized in that:
Said material is a kind of material that is selected from Nb and the pottery.
4. diffusion processing apparatus as claimed in claim 1 is characterized in that:
Said holding member makes said volumes relative with said R-Fe-B based rare earth sintered magnet not interdict the mode between said volumes and the said R-Fe-B based rare earth sintered magnet.
5. diffusion processing apparatus as claimed in claim 1 is characterized in that:
Said holding member keeps said volumes and said R-Fe-B based rare earth sintered magnet with the mode that is spaced apart 0.1mm～300mm of said volumes and said R-Fe-B based rare earth sintered magnet.
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