CN115213417B - Method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation - Google Patents

Method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation Download PDF

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CN115213417B
CN115213417B CN202210877949.4A CN202210877949A CN115213417B CN 115213417 B CN115213417 B CN 115213417B CN 202210877949 A CN202210877949 A CN 202210877949A CN 115213417 B CN115213417 B CN 115213417B
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hydrogenation
dehydrogenation
based alloy
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CN115213417A (en
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沙江波
廖军华
魏振河
彭徽
郭洪波
逄淑杰
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Beihang University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/023—Hydrogen absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/142—Thermal or thermo-mechanical treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/145—Chemical treatment, e.g. passivation or decarburisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/02—Alloys based on vanadium, niobium, or tantalum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Abstract

The invention discloses a method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation, which comprises the following steps: s1, proportioning, namely weighing Nb, si, ti, al, cr, hf, sc pure metal raw materials according to the proportion of the components; s2, smelting, namely putting the weighed raw materials into a smelting furnace for smelting; s3, hydrogenation, namely placing the Nb-Si-based alloy cast ingot into a hydrogenation dehydrogenation furnace, vacuumizing, raising the furnace temperature to the hydrogenation temperature, introducing hydrogen into the furnace body to the hydrogenation pressure, and preserving heat; obtaining hydrogenated-cracked Nb-Si-based alloy; s4, crushing, namely crushing and screening the hydrogenated Nb-Si-based alloy to obtain hydrogenated alloy powder; s5, dehydrogenation, namely carrying out vacuum high-temperature dehydrogenation on the hydrogenated alloy powder in a hydrogenation and dehydrogenation furnace to obtain Nb-Si-based dehydrogenated alloy powder. The method for preparing the Nb-Si-based alloy powder by hydrogenation and dehydrogenation can solve the problems of high production cost and long production period of the traditional Nb-Si-based alloy powder.

Description

Method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation
Technical Field
The invention relates to the technical field of preparation methods of Nb-Si-based alloy powder, in particular to a method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation.
Background
The Nb-Si-based alloy has high melting point, low density and excellent high-temperature strength, is the most potential material for replacing the existing nickel-based superalloy, has the temperature bearing capacity reaching 1200-1400 ℃, and has wide application prospect in the superhigh temperature fields of new generation high thrust ratio aeroengines, high thrust ratio rocket engine power equipment and the like. The Nb-Si based alloy consists essentially of Nb-based solid solution (Nb SS ) And intermetallic compound Nb 5 Si 3 Phase composition, formerProviding room temperature ductility, the latter providing strength and creep resistance at 1600 to 1800 ℃. In order to balance the room temperature toughness, high temperature strength and oxidation resistance of the Nb-Si-based alloy, ti, al, cr, hf and other elements are added for alloying, so that the comprehensive performance of the alloy is obviously improved.
The preparation process has important influence on the structure and the performance of the material. At present, the preparation method of the Nb-Si-based alloy mainly comprises vacuum arc melting, directional solidification, investment casting and the like. However, the alloy prepared by the arc melting method has more serious element segregation, and Nb SS And Nb (Nb) 5 Si 3 The phase structure is coarse, so that the room temperature fracture toughness and the high temperature oxidation resistance of the alloy are far lower than target values, and the engineering application of the Nb-Si-based alloy is greatly limited. In addition, it is difficult to manufacture Nb-Si-based alloy parts having a complex shape by machining due to the intrinsic brittleness and work hardening of the silicide. In recent years, powder metallurgy methods and additive manufacturing methods have attracted attention from more and more researchers. The powder metallurgy method can better control the phase scale, proportion, morphology, distribution and the like in the alloy, is hopeful to realize tissue control, obtains optimized tissue and improves the comprehensive performance of the alloy. Additive manufacturing methods can achieve customization of microstructure during the forming process by adjusting the forming parameters to produce complex shaped members with excellent properties.
The powder raw material excellent in combination properties is a prerequisite for the suitability of Nb-Si based alloys for powder metallurgy processes and additive manufacturing processes. The traditional alloy powder preparation process mainly relates to mechanical alloying and atomization technology, such as an argon atomization method (Argon atomization, AA) which is to melt metal in a crucible under vacuum condition, then to atomize and break up the metal liquid into a large number of tiny liquid drops under the gas protection condition, wherein the liquid drops are solidified into spherical or nearly spherical particles in flight, but the Nb-Si-based alloy is easy to be mixed with nonmetallic substances due to the high melting point and high activity of the Nb-Si-based alloy. Although the spherical powder prepared by the plasma rotary electrode atomization method (Plasma Rotating Electrode Atomization, PREA) is suitable for powder metallurgy and additive manufacturing methods, the low yield of fine powder and high cost limit its wide application, and thus it is necessary to develop a more efficient low-cost short-flow Nb-Si-based alloy powder production method.
Disclosure of Invention
The invention aims to provide a method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation, which solves the problems of high production cost and long production period of the existing Nb-Si-based alloy powder.
To achieve the above object, the present invention provides a method for preparing Nb-Si based alloy powder by hydrogenation and dehydrogenation, comprising the steps of:
s1, proportioning, namely weighing Nb, si, ti, al, cr, hf, sc pure metal raw materials according to the proportion of the components;
s2, smelting, namely putting the weighed raw materials into a smelting furnace for smelting to obtain Nb-Si-based alloy ingots with uniform components;
s3, hydrogenation, namely placing the Nb-Si-based alloy cast ingot into a hydrogenation dehydrogenation furnace, vacuumizing, raising the furnace temperature to the hydrogenation temperature, introducing hydrogen into the furnace body to the hydrogenation pressure, and preserving heat; obtaining hydrogenated-cracked Nb-Si-based alloy;
s4, crushing, namely crushing and screening the hydrogenated Nb-Si-based alloy to obtain hydrogenated alloy powder;
s5, dehydrogenation, namely carrying out vacuum high-temperature dehydrogenation on the hydrogenated alloy powder in a hydrogenation and dehydrogenation furnace to obtain Nb-Si-based dehydrogenated alloy powder.
Preferably, in the S1, the atomic percentage content ratio of Nb, si, ti, al, cr, hf, sc is Nb-16Si-24Ti-2Al-2Hf-2Cr-0.3Sc.
Preferably, in the step S1, the raw materials are put into acetone and absolute ethyl alcohol for ultrasonic cleaning before being weighed.
Preferably, in the step S2, the raw materials are put into a vacuum non-consumable arc furnace for smelting, and the smelting is repeated for 5-6 times.
Preferably, in the step S3, the hydrogenation and dehydrogenation furnace is vacuumized to 5X 10 -3 Pa, the hydrogenation temperature is 200-300 ℃, and the heating rate is 5-10 ℃ per minute.
Preferably, in the step S3, the hydrogenation pressure is 2.5-3.5MPa, and the heat preservation time is 1-2h.
Preferably, in S4, the particle size of the hydrogenated alloy powder is 45-105. Mu.m.
Preferably, in the step S5, the dehydrogenation vacuum degree is 5×10 -3 Pa, dehydrogenation temperature is 600-800 ℃, and dehydrogenation time is 2h.
The method for preparing Nb-Si-based alloy powder by adopting hydrogenation and dehydrogenation has the advantages and positive effects that:
1. the Nb-Si-based alloy is subjected to hydrogenation treatment, silicide in the Nb-Si-based alloy generates cracks and expands, the alloy surface is continuously cracked and peeled to generate powder, and Nb in the Nb-Si-based alloy SS The phase expansion facilitates the comminution of Nb-Si based alloys.
2. The Nb-Si-based alloy is produced by adopting a hydrogenation dehydrogenation furnace, so that the equipment investment is low, the production process parameters are easy to set, the cost of the Nb-Si-based alloy powder is reduced, and the production period is shortened.
3. The Nb-Si-based alloy block is prepared by using hydrogenated and dehydrogenated powder with the particle size of 45-105 mu m as a raw material and using a laser cladding additive manufacturing method, and fluorescence analysis shows that the block has no crack inside.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 shows the macroscopic morphology and microstructure of Nb-16Si-24Ti-2Al-2Cr-2Hf-0.3Sc alloy before and after hydrogenation, prepared in example one of the methods for preparing Nb-Si-based alloy powder by hydrogenation and dehydrogenation of the present invention;
FIG. 2 is an XRD pattern of an as-cast alloy of Nb-16Si-24Ti-2Al-2Cr-2Hf-0.3 prepared in examples 1-9 of a process for preparing Nb-Si-based alloy powders by hydrodeoxygenation according to the invention;
FIG. 3 is a back-scattered image of a hydrogenated alloy cross-section microstructure and elemental distribution of example 1 of a method of preparing Nb-Si based alloy powders by hydrogenation dehydrogenation in accordance with the present invention;
FIG. 4 is a bar graph showing oxyhydrogen content of Nb-Si-based alloy powders according to examples 1-9 of the method for preparing Nb-Si-based alloy powders by hydrogenation and dehydrogenation in accordance with the present invention;
FIG. 5 is an XRD pattern of an Nb-Si-based dehydrogenated alloy powder of examples 10-12 of the method of producing an Nb-Si-based alloy powder by hydrogenation dehydrogenation according to the present invention;
FIG. 6 is a bar graph of oxyhydrogen content of a Nb-Si-based dehydrogenated alloy powder of examples 10-12 of a method for preparing a Nb-Si-based alloy powder by hydrogenation dehydrogenation in accordance with the present invention;
FIG. 7 is a graph showing changes in morphology of Nb-Si-based alloy powders before and after dehydrogenation in accordance with example 2 of the method for preparing Nb-Si-based alloy powders by hydrogenation and dehydrogenation in accordance with the present invention;
FIG. 8A macroscopic morphology of a bulk Nb-Si-based alloy prepared by laser cladding of Nb-Si-based dehydrogenated alloy powder obtained in example 11 of the method of preparing Nb-Si-based alloy powder by hydrogenation dehydrogenation in accordance with the present invention;
FIG. 9 is a schematic diagram of a hydrogenation/dehydrogenation furnace according to an embodiment of the method for producing Nb-Si-based alloy powder by hydrogenation/dehydrogenation according to the present invention.
Detailed Description
The technical scheme of the invention is further described below through the attached drawings and the embodiments.
A method for preparing Nb-Si based alloy powder using hydrogenation dehydrogenation, comprising the steps of:
s1, proportioning, namely weighing pure metal raw materials of Nb with the purity of 99.99%, si with the purity of 99.999%, ti with the purity of 99.995%, al with the purity of 99.999%, cr with the purity of 99.95%, hf with the purity of 99.95% and Sc with the purity of 99.95% according to the component proportions. The atomic percentage content of Nb, si, ti, al, cr, hf, sc is Nb-16Si-24Ti-2Al-2Hf-2Cr-0.3Sc. Before the raw materials are weighed, the raw materials are put into acetone and absolute ethyl alcohol for ultrasonic cleaning.
S2, smelting, namely putting 150g of weighed raw materials into a vacuum non-consumable arc furnace for smelting, and repeatedly smelting for 5-6 times to ensure that alloy components are uniform and obtain an Nb-Si-based alloy cast ingot with uniform components.
S3, FIG. 9 is a schematic diagram of a hydrogenation dehydrogenation furnace according to an embodiment of the method for preparing Nb-Si-based alloy powder by hydrogenation and dehydrogenation. As shown in FIG. 9, the Nb-Si-based alloy ingot is hydrogenated, put into a hydrogenation and dehydrogenation furnace, and the equipment is vacuumizedVacuumizing to 5×10 -3 Pa. Raising the furnace temperature to the hydrogenation temperature of 200-300 ℃ according to the heating rate of 5-10 ℃/min; introducing hydrogen into the furnace body to hydrogenation pressure of 2.5-3.5MPa, and preserving heat for 1-2h; cooling to room temperature to obtain hydrogenated-cracked alloy powder. The hydrogen will pass through the gas purifying furnace before entering the hydrogenation dehydrogenation furnace, and the high purity titanium sponge in the furnace is used for purifying the hydrogen so as to minimize the influence of carbon, nitrogen and oxygen impurities mixed in the hydrogen on the hydrogenation process.
S4, crushing, namely mechanically crushing and screening the hydrogenated Nb-Si-based alloy to obtain hydrogenated alloy powder; the particle size of the hydrogenated alloy powder is 45-105 μm.
S5, dehydrogenation, namely carrying out vacuum high-temperature dehydrogenation on the hydrogenated alloy powder in a hydrogenation and dehydrogenation furnace to obtain Nb-Si-based dehydrogenated alloy powder. Dehydrogenation vacuum degree is 5×10 -3 Pa, dehydrogenation temperature is 600-800 ℃, and dehydrogenation time is 2h.
The main influencing factors in the hydrogenation process are hydrogenation temperature, pressure and time, and the hydrogenation fragmentation condition of the Nb-Si-based alloy without hydrogenation temperature, pressure and time is studied through orthogonal experiments. Examples 1-9 the process parameters set up during hydrogenation are shown in table 1.
Table 1 examples 1-9 process parameters during hydrogenation
Phase composition analysis was performed on the molten Nb-Si based alloy ingot, hydrogenated alloy powder and dehydrogenated alloy powder using a japanese D/MAX-2500 multifunctional X-ray diffraction (XRD). The Nb-Si-based alloy ingot was polished flat with a sand paper of particle size 2000, and the powder material was placed in a glass slide for measurement. XRD test adopts Cu K alpha target, lambda= 0.15405nm, working voltage is 40kV, current is 200mA, scanning speed is 5 DEG/min, and scanning range is 20-90 deg. After the test is completed, diffraction peaks are subjected to calibration analysis through Jade 6 software.
The particle size D50 value of the powder was measured using an LMS-30 laser particle sizer manufactured by Japanese Kogyo Co. The content of hydrogen and oxygen elements in alloy cast ingots and powder is measured by using an oxygen nitrogen hydrogen content analyzer of Beijing steel Minak-Ke ONH-3000 type, and the testing principles of the content of hydrogen and oxygen elements are respectively an inert gas pulse melting thermal conductivity method and a pulse heating inert gas melting-infrared absorption method.
Polishing Nb-Si-based alloy cast ingots sequentially by using frosted paper with granularity of 800-3000, and then using SiO 2 And (5) mechanically polishing the polishing solution. The powder morphology was characterized using the secondary electron mode of the ZEISSS UPRA55 field emission scanning electron microscope, the alloy microstructure and powder cross section were characterized using the back scattering mode, and the powder cross section element distribution was characterized using an electron microscope-attached energy spectrometer (EDS, energy Dispersive Spectrometer).
FIG. 1 shows the macroscopic morphology and microstructure of Nb-16Si-24Ti-2Al-2Cr-2Hf-0.3Sc alloy prepared by the first embodiment of the method for preparing Nb-Si-based alloy powder by hydrogenation and dehydrogenation, (a) the macroscopic morphology of the button-shaped alloy ingot cast by arc melting, (a ') the microstructure of the alloy observed in a scanning electron microscope back scattering mode, (b) the macroscopic morphology of the alloy after hydrogenation, and (b') the microstructure of the alloy after hydrogenation observed in a scanning electron microscope back scattering mode. As shown, the oxygen content in the Nb-Si based alloy ingot was 0.021wt.% and the hydrogen content was 0.0012wt.%. The as-cast alloy is mainly composed of Nb SS (light gray contrast), nb 3 Si (dark gray contrast) and beta-Nb 5 Si 3 (black contrast) composition, large area Nb is present in the alloy SS +Nb 3 Si and Nb SS +β-Nb 5 Si 3 Eutectic region, nb, known from Nb-Si binary phase diagram SS +Nb 3 Si eutectic is formed in the solidification process, nb SS +β-Nb 5 Si 3 Eutectic crystal is formed by Nb in solidification process 3 Si→Nb SS +β-Nb 5 Si 3 Eutectoid decomposition. The alloy ingot is broken into powder by hydrogenation for 1h under the conditions of the hydrogenation temperature of 200 ℃ and the hydrogenation pressure of 2.5MPa in example 1, and the particle size of most of the powder is less than 10The particle size of the powder is more than 200 mu m, and the hydrogenated powder with the particle size of 45-105 mu m can be obtained after mechanical crushing and screening.
Similar crushing effects were obtained by the hydrogenation processes of examples 2-9.
FIG. 2 is an XRD pattern of an as-cast alloy after and before hydrogenation of Nb-16Si-24Ti-2Al-2Cr-2Hf-0.3Sc alloy prepared in examples 1-9 of a method for preparing Nb-Si-based alloy powder by hydrogenation and dehydrogenation in accordance with the present invention. As shown in the figure, the Nb-Si-based as-cast alloy is composed of Nb SS 、Nb 3 Si and beta-Nb 5 Si 3 The phase composition is in accordance with the backscattering microstructure of fig. 1 (a'). The phase composition of the nine hydrogenated powders is Nb SS 、Nb 3 Si、β-Nb 5 Si 3 、NbH 2 And NbO phase, indicating Nb SS Absorbing hydrogen atoms to generate chemical reaction to generate hydride, nb SS The phase did not disappear indicating that only part of the Nb was present after the alloy reacted with hydrogen SS Phase generates NbH 2 A phase which is also sufficient to fracture the alloy into small particle powders while part of Nb SS The phase absorbs oxygen in the hydrogen gas to form the NbO phase.
FIG. 3 is a back-scattered image of a cross-sectional microstructure of a hydrogenated alloy and the elemental distribution of example 1 of a method of preparing Nb-Si-based alloy powder by hydrogenation dehydrogenation in accordance with the present invention. As shown, cracks inside the hydrogenated powder are mainly concentrated in the silicide phase because of Nb SS The phase absorbs a large amount of hydrogen atoms to generate NbH 2 Volume expansion after phase, nb SS The fracture toughness of the phase can reach 28 MPa.m 1/2 While the fracture toughness of silicide phase is only 1-3 MPa.m 1/2 In Nb SS Internal Nb of alloy during phase expansion SS The phase and the silicide phase are mutually extruded, the silicide phase generates cracks firstly due to low fracture toughness, and the cracks propagate in the alloy along the silicide phase until the surface of the alloy is continuously cracked and peeled to generate powder.
The hydrides produced by the Nb-Si-based alloy ingots in the different embodiments are NbH 2 The degree of hydrogenation of the sample can be determined by measuring the change in the content of hydrogen element in the sample before and after the reaction. For the hydrogenated powders under the parameters of the examples by means of a polar analysisThe mass percent (wt.%) of hydrogen element is processed, and the priority of each factor influence in the experimental process can be ordered. Table 2 shows the results of the analysis of the variation in hydrogen content of examples 1 to 9.
Table 2 shows the results of the analysis of the variation in hydrogen content of examples 1 to 9
Wherein K is i (i=1, 2, 3) is the sum of the mass percentage increments of hydrogen element at various factor levels (hydrogenation temperature, pressure and time), G i (i=1, 2, 3) is the average value of the addition of the mass percentage increment of the hydrogen element under the influence of three hydrogenation process parameters, R is the extreme difference value (R=maximum average increment-minimum average increment) of the average weight increment of the same factor under different levels, and the influence degree of different factors on the hydrogenation process can be judged according to the value of each factor R. Generally, the larger R, the more pronounced the effect of this factor. The R value of the hydrogenation temperature, calculated as 0.4333, was far greater than 0.07 of the hydrogenation pressure and 0.06 of the hydrogenation temperature, R (hydrogenation temperature) was present>R (hydrogenation pressure)>Relationship of R (hydrogenation time). Thus, it can be determined that the hydrogenation temperature has the greatest effect on the hydrogenation process, followed by the hydrogenation pressure and the hydrogenation time has the least effect on the hydrogenation process.
Since the hydrogenation process is performed at higher temperatures, oxygen impurities are still present despite the purification of hydrogen, and the oxygen content of the powder can severely affect the formability and mechanical properties of Nb-Si based alloys produced by powder metallurgy and additive manufacturing methods. It is therefore necessary to study the law of influence of the hydrogenation process parameters on the variation of the oxygen content during the hydrogenation. Table 3 shows the results of the analysis of the oxygen element content of examples 1 to 9.
Table 3 shows the results of the analysis of the oxygen content of examples 1 to 9
Wherein K is i (i=1, 2, 3) is the sum of the oxygen element mass percent increment under the influence of three hydrogenation factors, G i (i=1, 2, 3) is the average value of the oxygen element mass percent increment added under the influence of three hydrogenation factors, R is the extreme difference value (R=maximum average increment-minimum average increment) of the average value of the same hydrogenation factor under different levels, and the R value of the hydrogenation time is calculated to be the largest, 0.0627, the R value of the hydrogenation temperature is similar to the R value, 0.0623, and the R value of the hydrogenation pressure is the smallest, 0.0443, so that R (hydrogenation time) exists>R (hydrogenation temperature)>Relationship of R (hydrogenation pressure). It can be determined that the hydrogenation time has the greatest effect on the oxygen uptake in the hydrogenation process, the effect of the hydrogenation temperature is slightly lower than the hydrogenation time, and the effect of the hydrogenation pressure is small.
FIG. 4 is a bar graph showing oxyhydrogen content of Nb-Si-based alloy powders according to examples 1-9 of the method for preparing Nb-Si-based alloy powders by hydrogenation and dehydrogenation in accordance with the present invention. As shown, the powders obtained in examples 1 to 9 showed a decreasing trend in hydrogen content and an increasing trend in oxygen content. The effect of the process parameters on the hydrogenation process was investigated in order to obtain a powder with high hydrogen absorption efficiency and low oxygen content, the hydrogenated powder of example 1 having a maximum hydrogen content of 1.4712wt.%, the hydrogenated powder of example 2 having a hydrogen content slightly lower than that of example 1 of 1.4312wt.%. In terms of oxygen content, the hydrogenated powder of example 4 had a minimum oxygen content of 0.171wt.%; while the hydrogenated powder of example 2 had an oxygen content of 0.176wt.%. In consideration of the comprehensive consideration of the hydrogen and oxygen content and the hydrogenation crushing effect, example 2 is the optimal hydrogenation process, namely the hydrogenation temperature is 200 ℃, the hydrogenation pressure is 3MPa, the hydrogenation time is 1.5h, and example 2 is taken as the raw material for the subsequent dehydrogenation experiment.
Examples 10-12 are studies of dehydrogenation processes at various process parameters, and the process parameters of examples 10-12 are shown in Table 4.
TABLE 4 examples 10-12 hydrogenation dehydrogenation process parameters
Sample numbering Hydrogenation temperature (. Degree. C.) Hydrogenation pressure (MPa) Hydrogenation time (h) Dehydrogenation temperature (. Degree. C.) Dehydrogenation time (h)
Example 10 200 3 1.5 600 2
Example 11 200 3 1.5 700 2
Example 12 200 3 1.5 800 2
FIG. 5 is an XRD pattern of Nb-Si-based dehydrogenated alloy powders of examples 10-12 of the method of preparing Nb-Si-based alloy powders by hydrogenation dehydrogenation according to the present invention. As shown in the figure, nbH 2 Cancellation ofLoss of phase of alloy of Nb SS 、Nb 3 Si、β-Nb 5 Si 3 And NbO phase, indicating that the hydrogenated powder is more fully dehydrogenated at all three hydrogenation temperatures. With the increase of dehydrogenation temperature, more and more hydrogen atoms are diffused out of the surfaces of the powder particles, and the powder starts to slowly flow out of NbH 2 Conversion to Nb SS 。
FIG. 6 is a bar graph showing oxyhydrogen content of Nb-Si-based dehydrogenated alloy powders of examples 10-12 of the method for producing Nb-Si-based alloy powders by hydrogenation dehydrogenation according to the present invention. As shown in the figure, the dehydrogenation temperature has a large influence on the oxyhydrogen content of the powder after dehydrogenation. After dehydrogenation, the hydrogen content of the sample is lower than 0.05wt.%, the hydrogen content gradually decreases with the increase of the dehydrogenation temperature, and the oxygen content is opposite. Hydrogen content at 600 ℃ is 0.046wt.%, oxygen content is 0.27wt.%; when the temperature was 800 ℃, the hydrogen content was reduced to 0.023wt.%, while the oxygen content was increased to 0.37wt.%; in comparison, when the dehydrogenation temperature is 700 ℃, the powder has a relatively optimal hydrogen-oxygen content, at which point the hydrogen content is 0.025wt.% and the oxygen content is 0.25wt.%.
FIG. 7 is a graph showing changes in morphology of Nb-Si-based alloy powders before and after dehydrogenation in accordance with example 2 of the method for preparing Nb-Si-based alloy powders by hydrogenation and dehydrogenation in accordance with the present invention; (a) And (a ') is the powder morphology and a partial magnified view of 86.3 μm D50 obtained by sieving the alloy after treatment under the process conditions of example 2, and (b) and (b') are the surface morphology of the dehydrogenated Nb-Si-based dehydrogenated alloy powder. As shown in the figure, the hydrogenated powder is in an irregular block shape, and the surface of the powder has an obvious lamellar structure, which indicates that the Nb-Si-based alloy is peeled off in lamellar form in the hydrogenation process. The surface morphology of the Nb-Si-based alloy hydrogenated powder under different hydrogenation process parameters is similar, and the surface morphology is respectively of a single-layer or multi-layer layered structure, and the surface of the Nb-Si-based alloy hydrogenated powder is of a smooth section; the second is a non-lamellar block whose surface is distributed with a large number of rough sections due to the differences in fracture of the hydrogenated powder from phase to phase, when the powder breaks apart from the silicide intermediate, the surface is smooth, when the powder breaks apart from Nb SS Phase middle fracture is rough section. The surface morphology of the dehydrogenated powder is similar to that of the hydrogenated powder, and the dehydrogenated powder is irregular block-shapedThe dehydrogenation process caused the powder to undergo secondary crushing to produce a plurality of fine particles of less than 10 μm in size and a D50 of 28.4. Mu.m.
FIG. 8 shows the macroscopic morphology of a bulk Nb-Si-based alloy prepared by laser cladding and additive coating of Nb-Si-based dehydrogenated alloy powder obtained in example 11 of the method for preparing Nb-Si-based alloy powder by hydrogenation dehydrogenation, wherein (a) is a macroscopic morphology graph, and (b) is a fluorescence analysis graph. As shown in the figure, the particle size of the hydrogenated-dehydrogenated powder is 45-105 mu m, and the Nb-Si-based alloy block is prepared under the conditions of 1000W of laser power, 600mm/s of scanning speed and 0.8mm of scanning interval, and the fluorescence analysis shows that the block has no cracks.
Therefore, the method for preparing the Nb-Si-based alloy powder by hydrogenation and dehydrogenation can solve the problems of high production cost and long production period of the traditional Nb-Si-based alloy powder.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that: the technical scheme of the invention can be modified or replaced by the same, and the modified technical scheme cannot deviate from the spirit and scope of the technical scheme of the invention.

Claims (5)

1. A method for preparing Nb-Si based alloy powder by hydrogenation and dehydrogenation, comprising the steps of:
s1, proportioning, namely weighing Nb, si, ti, al, cr, hf, sc pure metal raw materials according to the proportion of the components;
s2, smelting, namely putting the weighed raw materials into a smelting furnace for smelting to obtain Nb-Si-based alloy ingots with uniform components;
s3, hydrogenation, namely placing the Nb-Si-based alloy cast ingot into a hydrogenation dehydrogenation furnace, vacuumizing, raising the furnace temperature to the hydrogenation temperature, introducing hydrogen into the furnace body to the hydrogenation pressure, and preserving heat; obtaining hydrogenated-cracked Nb-Si-based alloy;
s4, crushing, namely crushing and screening the hydrogenated Nb-Si-based alloy to obtain hydrogenated alloy powder;
s5, dehydrogenation, namely carrying out vacuum high-temperature dehydrogenation on the hydrogenated alloy powder in a hydrogenation and dehydrogenation furnace to obtain Nb-Si-based dehydrogenated alloy powder;
in the S1, the atomic percentage content ratio of Nb, si, ti, al, cr, hf, sc is Nb-16Si-24Ti-2Al-2Hf-2Cr-0.3Sc;
in the step S3, the hydrogenation and dehydrogenation furnace is vacuumized to 5 multiplied by 10 -3 Pa, the hydrogenation temperature is 200-300 ℃, and the heating rate is 5-10 ℃/min;
in the step S3, the hydrogenation pressure is 2.5-3.5MPa, and the heat preservation time is 1-2h.
2. A method for producing Nb-Si based alloy powder using hydrogenation and dehydrogenation according to claim 1, wherein: in the step S1, before the raw materials are weighed, the raw materials are placed into acetone and absolute ethyl alcohol for ultrasonic cleaning.
3. A method for producing Nb-Si based alloy powder using hydrogenation and dehydrogenation according to claim 1, wherein: in the step S2, the raw materials are put into a vacuum non-consumable electric arc furnace for smelting, and the smelting is repeated for 5-6 times.
4. A method for producing Nb-Si based alloy powder using hydrogenation and dehydrogenation according to claim 1, wherein: in S4, the particle size of the hydrogenated alloy powder is 45-105 mu m.
5. A method for producing Nb-Si based alloy powder using hydrogenation and dehydrogenation according to claim 1, wherein: in the step S5, the vacuum degree of dehydrogenation is 5 multiplied by 10 -3 Pa, dehydrogenation temperature is 600-800 ℃, and dehydrogenation time is 2h.
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Citations (2)

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US5993732A (en) * 1997-07-11 1999-11-30 Mitsubishi Materials Corporation Method for manufacturing a rare earth magnetic powder having high magnetic anisotropy

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