CN1743105A

CN1743105A - Dysprosium-iron alloy powder preparation by reduction diffusion method

Info

Publication number: CN1743105A
Application number: CN 200410075389
Authority: CN
Inventors: 任英良; 段莉萍; 任忠平
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-08-30
Filing date: 2004-08-30
Publication date: 2006-03-08
Anticipated expiration: 2024-08-30
Also published as: CN100482384C

Abstract

The invention discloses a fabrication method of Fe2Dy alloy powder of compound among the metals, which takes Ca and Chloride NaCl(CaCl2) as reducer, the Fe2Dy alloy powder in which the Dy content is 45-59% is made directly from rare earths oxide (Dy2O3) via reduction diffusion process, The method comparing with the present technology is benefit to the metal diffusion and the compound because the melting point of CaO.NaCl and 2CaO.CaCl2 are low ( melting point respective is 801 deg.C and 782 deg.C). Advantages: no pollution, simple craftwork, Dy content of alloy is controllable and stable, low cost and suitable for making rare earths permanent-magnet and magneto optical material.

Description

Direct prepn. of Dy-Fe alloy powder by reduction diffusion method

Technical Field

The invention relates to a method for preparing intermetallic compound type alloy powder, in particular to Dy-Fe (Fe)₂Dy) alloy powder, belonging to the technical field of new materials

Background

The rare earth permanent magnet material (NdFeB) is mainly prepared from metals such as rare earth metal neodymium (Nd) iron, boron and the like through a powder metallurgy process, is widely applied to industries such as electronics, machinery and the like, particularly high-performance materials, is applied to national defense industry, and has a very wide market shadow.

In order to greatly improve the magnetic performance of the rare earth permanent magnet material (NdFeB), especially improve the intrinsic coercivity and the thermal stability, a small amount of rare earth metal dysprosium is often added during the powder metallurgy smelting of the rare earth permanent magnet material (NdFeB), so that the thermal stability of the rare earth permanent magnet material (NdFeB) is improved, that is, the magnetic performance of the rare earth permanent magnet material (NdFeB) is not obviously reduced under the condition of higher use temperature, and 1% -10% of dysprosium is usually added into the NdFeB permanent magnet material.

Besides being used as additive of rare earth permanent magnetic material (NdFeB), the rare earth metal dysprosium can also be used in other rare earth functional materials, such as rare earth super magnetostrictive alloy (FeDy)_0.7b_0.3) And magneto-optical storage material (FeDyTbGd).

In the rare-earth functional material, the rare-earth metal dysprosium is added in the form of pure metal. According to the principle of the smelting process, the addition of alloying elements in the form of master alloys is more favourable for alloying than in the form of pure metals, since the melting points of master alloys are generally lower than those of pure metals. Therefore, the smelting process is more beneficial to melting, and the alloy components are more uniform.

Because the metal dysprosium is in the alloy containing iron in practical application, the dysprosium iron (Fe) is used₂Dy) is added into the master alloy particularly reasonably. Viewed from another perspective, dysprosium iron (Fe)₂Dy) alloy is simple in production process and low in production cost.

Currently, there are three general methods for preparing dysprosium-iron (DyFe) alloys. Firstly, pure dysprosium is prepared by rare earth fluoride through a calcium thermal reduction method, and then the dysprosium-iron alloy with different dysprosium contents is smelted through a eutectic method. Second, the dysprosium-iron alloy with high dysprosium content is prepared by eutectoid electrolysis. Thirdly, dysprosium-iron alloy is directly prepared from oxides by using a pure calcium reduction diffusion method. The disadvantages of these preparation methods are respectively: the dysprosium-iron alloy prepared by the eutectic method has the defects of high production cost, serious environmental pollution and the like; the dysprosium-iron alloy prepared by the eutectoid electrolysis method has uncontrollable dysprosium content in a certain range, which brings difficulty to use; the calcium reduction diffusion method has the advantages of no environmental pollution, controllable alloy components and the like. However, the simple use of calcium as a reducing agent has the following disadvantages: the melting point of the reduction product calcium oxide is as high as 2600 ℃, the calcium oxide is still solid at the reduction temperature, the calcium oxide has a barrier effect on the diffusion of the reduced rare earth metal dysprosium, and even the reduced metal dysprosium is contained by the calcium oxide, so that not only is the difficulty brought to the purification of the alloy, but also the calcium oxide cannot form a dysprosium-iron alloy with the metal iron. Therefore, in order to form dysprosium-iron alloy with fixed composition, the addition amount of dysprosiumoxide is larger than the theoretical amount, and the dysprosium oxide is usually added in an amount of 110-120%, so that the production cost is greatly increased.

Disclosure of Invention

The invention aims to provide a novel production process for overcoming the defects of overhigh production cost, serious environmental pollution, unstable alloy components and the like in the related technologies, and has the main advantages of simple process, no environmental pollution and lower production cost₂Dy) alloy powder.

The invention can be realized by the following technical scheme: Dy-Fe (Fe)₂Dy) alloy powder is prepared from calcium chloride (NaCl + CaCl)₂) Direct prepn. of Dy-Fe (Fe) as reducer₂Dy) alloy powder. CaO, NaCl, 2CaO, CaCl with low melting point in reduction process₂(melting points 801 ℃ and 782 ℃ respectively), and is more favorable for the diffusion of reduced metal and the formation of intermetallic compounds. The dysprosium content in the alloy powder is 45-59 percent (weight), and the reduction diffusion chemical reaction equation is as follows:

……(1)

……(2)

……(3)

the preparation process comprises the following steps: a certain amount of dysprosium oxide powder, metal calcium particles, iron powder, NaCl and CaCl₂(where Ca is 1.5 times the theoretical amount, NaCl and CaCl)₂15% of the amount of Ca used, the other being the theoretical amount) are mixed with the powderUniformly mixing for more than 1.5 hours, and then putting the mixture at 500 Kg-800 Kg/cm on a press²Pressure ofPressing into ring material block, vacuum-pumping in vacuum resistance furnace to 2Pa, cleaning with pure argon gas for 2-3 times, and filling argon gas under positive pressure protection to heat for reduction and diffusion reaction to obtain dysprosium-iron alloy with different dysprosium contents. Because of different dysprosium content, the dysprosium content in the alloy can be controlled, and generally the dysprosium content can be changed within the range of 45-50%. When the dysprosium content reaches 59%, the alloy composition is Fe₂Dy intermetallic compounds; when the dysprosium content is less than 59%, the alloy composition is Fe₂Dy or Fe₂₃Dy₆Intermetallic compound and metal dysprosium, the temperature of reduction and diffusion reaction is 950-1100 ℃, the holding time is 7-10 hours, the sample is cooled along with the furnace after the reaction is finished, the sample can be taken out of the furnace when the sample is cooled to below 60 ℃, and the sample taken out of the furnace can be directly put with 5-10% NH₄Soaking the obtained product in a Cl aqueous solution for at least 5 hours, washing the obtained product with water under the condition of stirring until the obtained solution turns brown from white, then washing the obtained product with 2-4% (volume) acetic acid aqueous solution and 1% EDTA ammonia water solution for 1-2 times, finally washing the obtained product with clear water until the pH value of the obtained solution is neutral, washing the obtained product with water for 2-3 times under the condition of filtering, washing the obtained product with absolute ethyl alcohol for 2 times, drying the obtained product in a vacuum drying box at 60 ℃, taking out the obtained product after 1-2 hours, and carrying out vacuum packaging to obtain the final product.

Compared with the prior art, the invention has the beneficial effects that calcium chloride salt (NaCl + CaCl) is adopted₂) The reduction diffusion method directly forms Fe with dysprosium content of 59 percent from metal dysprosium oxide through reduction diffusion and iron₂The Dy intermetallic compound has no environmental pollution, low production cost, stable and controllable dysprosium content and high practical value.

Detailed Description

The present invention will be further described with reference to the following examples

Example 1

Dy is reacted with₂O₃236.2 g, 148.8 g of Fe powder, 113.6 g of Ca particles, 17 g of NaCl, CaCl₂17 g of the mixture is evenly mixed by a mixer and then is mixed with 500Kg/cm²Pressing the sample into a circular material block under pressure, placing the circular material block into a reactor, placing the reactor into a resistance heating furnace, vacuumizing the reactor to 2Pa, then filling Ar gas, heating the circular material block to 950 ℃ under the protection of the Ar gas, preserving the temperature for 10 hours, then cooling the circular material block along with the furnace to below 60 ℃, taking out the sample, and placing the sample in 5% NH₄Soaking in a Cl aqueous solution for 6 hours, washing with water under stirring until the solution turns brown, then washing with 2% (volume) acetic acid aqueous solution and 1% EDTA ammonia aqueous solution for 2 times, washing with water until the solution becomes neutral (pH value), filtering, washing with absolute ethyl alcohol for 2 times, and then carrying out vacuum drying to obtain 351.2 g of alloy powder, wherein the alloy contains 58.1% Dy, 40.5% Fe, 0.12% Ca and 0.21% O.

Example 2

Dy is reacted with₂O₃750 g, 360 g Ca particles, 450 g Fe powder, 54 g NaCl, CaCl₂54 g of circular ring-shaped material block prepared by the method of example 1 was put into a heating furnace, heated to 1000 ℃ under the protection of Ar gas, and the reaction material was treated by the method of example 1 with heat preservation for 8 hours, and 1047.3 g of alloy powder was obtained, wherein the alloy contained 58.1% Dy, 40.9% Fe, 0.15% Ca, and 0.25% O.

Example 3

Dy is reacted with₂O₃1000 g, 480 g of Ca particles, 600 g of Fe powder, 72 g of NaCl and CaCl₂72 g of ring-shaped material block prepared by the method of example 1 was put into a heating furnace, heated to 1100 ℃ under the protection of Ar gas, and kept warm for 7 hours, and the reaction mass was processed by the method of example 1, to obtain 1381.6 g of alloy powder, which contains 58.4% Dy, 40.5% Fe, 0.14% Ca, and 0.24% O.

Example 4

Dy is reacted with₂O₃480 g, 230 g of Ca particles, 501 g of Fe powder, 34.5 g of NaCl and CaCl₂34.5 g of a circular ring-shaped material block prepared by the method of example 1 was put into a heating furnace, heated to 1100 ℃ under the protection of Ar gas, and kept warm for 7 hours, and then the reaction material was treated by the method of example 1 to obtain alloy powder854.3 g, the alloy contains 45.1% Dy, 53.5% Fe, 0.11% Ca, 0.27% O.

Example 5

Dy is reacted with₂O₃850 g, 408 g of Ca particles, 710 g of Fe powder, 61 g of NaCl, CaCl₂61 g of circular ring-shaped material block prepared by the method of example 1 was put into a heating furnace, heated to 1100 ℃ under the protection of Ar gas, and heat-preserved for 7 hours, and then the reaction material was processed by the method of example 1, so that 1355.3 g of alloy powder was obtained, wherein the alloy contained 51.4% Dy, 47.2% Fe, 0.10% Ca, and 0.22% O.

Example 6

Dy is reacted with₂O₃4500 g, 2160 g of Ca particles, 2700 g of Fe powder, 324 g of NaCl and CaCl₂324 g of circular ring-shaped material block prepared by the method of the embodiment 1 is put into a heating furnace, heated to 1100 ℃ under the protection of Ar gas, and kept warm for 9 hours, and the reaction material is treated by the treatment method of the embodiment 1 after being taken out of the furnace, so that 6218.2 g of alloy powder is obtained, wherein the alloy contains 58.5 percent of Dy, 40.5 percent of Fe, 0.13 percent of Ca and 0.12 percent of O.

2500 g of the alloy powder obtained in example 6 was used, 18 kg and 15 kg of neodymium-iron-boron alloy were successively melted in a 20 kg vacuum induction furnace, and after a magnet was produced, the magnetic properties thereof were comparable to those of a magnet added with conventional Fe-80Dy, but the intrinsic coercive force was improved.

Claims

1. Intermetallic compound Dy-Fe₂Dy) alloy powder, which is characterized in that: adopts metal calcium and chloride salt (NaCl and CaCl)₂) As reducing agents, directly from rare earth oxides (Dy)₂O₃) Dysprosium iron (Fe) containing dysprosium 45-59 wt% is prepared by reduction diffusion₂Dy) alloy powder.

The ingredients are calculated according to the following chemical reaction equation:

firstly, a certain amount of dysprosium oxide, metallic calcium particles, iron powder, sodium chloride and calcium chloride are uniformly mixed by a mixerMixing for more than 1.5 hours, and then putting the mixture at 500 Kg-800 Kg/cm on a press²The material is pressed into a ring-shaped material block, the ring-shaped material block is placed in a vacuum resistance furnace, after the vacuum resistance furnace is vacuumized to 2Pa, the ring-shaped material block is cleaned for 2 to 3 times by pure argon, and then the ring-shaped material block is filled with argon and heated under the protection of positive pressure to carry out the original reduction diffusion reaction, and the main technical characteristics are that: the dosage of Ca in the reducing agent is 1.5 times of the theoretical amount, and NaCl and CaCl₂The calculated amount is 15 percent of the Ca amount, and the reduction diffusion reaction temperature of other materials is 950-1100 ℃ according to the theoretical amount. Keeping the temperature for 7 to 10 hours, cooling the sample along with the furnace after the reaction is finished, and discharging the sample when the temperature of the sample is cooled to be below 60 ℃.

2. The method for producing an alloy powder as set forth in claim 1, wherein: the cooled material after being discharged is directly put into 5 to 10 percent of NH₄Soaking in Cl aqueous solution for 5 hours, washing with water under the condition of stirring until the solution turns brown from white, then washing with 2-4% (volume) acetic acid aqueous solution and 1% EDTA ammonia water solution for 1-2 times, finally washing with clear water until the pH value of the solution is neutral, filtering, washing with absolute ethyl alcohol for 2 times, placing the precipitated alloy powder in a vacuum drying oven below 60 ℃ for drying for 1-2 hours, taking out and carrying out vacuum packaging to obtain the final product.