FeCoNbW alloy target material and hot isostatic pressing preparation method thereof

Abstract

The invention discloses a FeCoNbW alloy target material and a hot isostatic pressing preparation method thereof, and belongs to the technical field of magnetic storage target material manufacturing. The method comprises the following steps: carrying out vacuum melting on Fe blocks, Co blocks and Nb blocks, and then carrying out gas atomization to obtain FeCoNb alloy powder; the FeCoNbW alloy target material is obtained by mixing the FeCoNbW alloy powder and W powder, and then sequentially carrying out sheathing, die filling, degassing, gradient hot isostatic pressing sintering and machining on the FeCoNbW alloy powder and the W powder. The W powder is added into the FeCoNb alloy powder to be combined into mixed powder of target components, the FeCoNb alloy powder forms metal alloy due to the components, demagnetization can be achieved, and the final magnetic permeability of the target material is improved. And then the target blank is sintered in a gradient hot isostatic pressing mode, the problems that components are not uniform, the target blank cracks during conventional plastic deformation and the magnetic permeability is low are solved, and the yield of the FeCoNbW alloy target is effectively increased.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic storage target material manufacturing, and in particular relates to a FeCoNbW alloy target material and a hot isostatic pressing preparation method thereof. Background Art

[0002] Fe-Co alloy is a soft magnetic material with excellent performance, with extremely high saturation flux density Bs (2.4T) and Curie temperature (980-1100℃), so it is suitable for making aviation electrical appliances (micro motors, electromagnets, relays, etc.) that require light weight, small size and high operating temperature. In addition, it has a large saturation magnetostriction coefficient λs, which can be used to make magnetostrictive transducers and various magnetic recording equipment, such as new sensors, magnetic recording read heads, filters, etc. Doping a small amount of Nb into Fe-Co alloy can react with impurities in the alloy to improve the soft magnetic properties of the alloy. On the other hand, it forms a Co-Nb local disordered area with Co and refines the size of the grains.

[0003] In order to further improve the magnetic properties of FeCoNb alloys, by introducing tungsten (W) into the alloy system, the hardness and wear resistance of the soft magnetic alloy material can be improved while maintaining good magnetic properties. There are generally two conventional methods for preparing target materials. One is to prepare by forging, rolling and heat treatment after smelting and casting. This method is suitable for metals or alloys with good plastic deformation ability; the other is to prepare by powder metallurgy. This method is suitable for difficult-to-deform metals or high-temperature alloys. For FeCoNbW alloys, due to the addition of W with extremely high melting point and extremely high hardness, although the hardness of the alloy is increased, the plastic deformation ability of the alloy is reduced. Therefore, it is difficult to prepare FeCoNbW alloy targets by smelting processing and plastic deformation. In addition, the prior art has not disclosed a method for preparing FeCoNbW alloy targets. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a FeCoNbW alloy target by hot isostatic pressing to solve the problem of low yield of the FeCoNbW alloy target; and a FeCoNbW alloy target prepared by hot isostatic pressing.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] In a first aspect, a hot isostatic pressing method for preparing a FeCoNbW alloy target comprises the following steps:

[0007] Step 1, vacuum melting Fe blocks, Co blocks, and Nb blocks and then atomizing them to obtain FeCoNb alloy powder;

[0008] Step 2, FeCoNb alloy powder and W powder are mixed to obtain FeCoNbW alloy powder, and the powder is subjected to encapsulation, molding, degassing, gradient hot isostatic pressing sintering, and machining in sequence to obtain FeCoNbW alloy target;

[0009] The specific sintering process of the gradient hot isostatic pressing sintering is as follows:

[0010] First temperature increase and pressurization: pressurize from cold state to 45-55MPa, and at the same time heat from room temperature (25-30℃) to 700-800℃ at the first heating rate, keep the temperature and pressure and calcine for 50-70min, and naturally increase the pressure during the temperature increase process;

[0011] Second heating and pressurizing: During the heating process, the pressure is increased at the same time, from 700-800°C to 950-1050°C at the second heating rate, and the pressure is ≥110MPa when the temperature is reached. The sintering temperature is 950-1050°C and the sintering pressure is ≥110MPa, and the calcination is carried out for 180-240min under the conditions of heat preservation and pressure maintenance for 180-240min;

[0012] The third step is to reduce temperature and pressure: after calcination, the temperature and pressure will naturally decrease to ≤100℃.

[0013] Furthermore, the mass percentage of elements in the FeCoNbW alloy target is Fe: 10-20at%, Nb: 4-6at%, W: 10-20at%, and the balance is Co.

[0014] Furthermore, the atomization pressure of the gas atomization is 3.6 MPa, the atomization temperature is 1650° C., and the atomization gas is argon.

[0015] Furthermore, the oxygen content of the FeCoNb alloy powder is ≤400ppm, and the particle size is <150 mesh.

[0016] Furthermore, the purity of W powder is ≥3N5, and the particle size is -325 mesh.

[0017] Furthermore, the powder is mixed using a V-type powder mixer, which is filled with argon gas to protect against air entry, and the powder mixing time is 20-30 hours.

[0018] Furthermore, the stainless steel type used for the sheath is SUS304 or SUS316L, the flatness of the mold is less than 1 mm, and high-temperature cotton is placed between the FeCoNbW alloy powder and the sheath to prevent Fe and C from reacting.

[0019] Furthermore, the degassing temperature is 400-600°C, and the vacuum degree in the package is less than 2×10 -3 Pa.

[0020] Furthermore, the first heating rate is 9-11°C / min, and the second heating rate is 4-6°C / min.

[0021] Furthermore, the machining uses a CNC grinder to process the thickness, and the wire cutting is used to cut the shape to the finished size, and then it is cleaned, dried and packaged.

[0022] In a second aspect, a FeCoNbW alloy target is prepared by the above-mentioned hot isostatic pressing method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention provides a hot isostatic pressing preparation method for FeCoNbW alloy target material, which adopts FeCoNb alloy powder and W powder to form a mixed powder of target components. Since the components of FeCoNb alloy powder form a metal alloy, it can be demagnetized to improve the final magnetic permeability of the target material. Then, the target blank is sintered by gradient hot isostatic pressing to solve the problems of uneven components, cracking of the target blank during conventional plastic deformation, and low magnetic permeability, thereby effectively improving the yield rate of FeCoNbW alloy target material. The prepared target material has a composition control accuracy of ±0.2at%, a deviation of less than 0.5% at each location, uniform and fine grains (<50um), no internal defects, and a smooth surface. According to the ASTM F2086-01 standard, the magnetic permeability is ≥30%, which meets the use requirements.

[0025] 2. The alloy target material obtained by the preparation method of the present invention has a purity of ≥3N5 (99.95%) and a density of ≥99%. It is composed of the following elements in atomic percentage: Fe: 10-20at%; W: 10-20at%; Nb: 4-6at%, and the balance is Co. It has the advantages of precise finished product composition control, uniform composition distribution, no segregation, no inclusions, fine and uniform grains, high purity of the finished product, high density, high and uniform magnetic permeability, etc. The target material is suitable for magnetron sputtering and has good soft magnetic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 It is a schematic diagram of the process flow of hot isostatic pressing preparation of a FeCoNbW alloy target material of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] See also Figure 1 A hot isostatic pressing method for preparing a FeCoNbW alloy target comprises the following steps:

[0031] Step 1, weigh Fe block, Co block, Nb block and W powder according to the element mass percentage of Fe: 15at%, Co: 65at%, Nb: 5at%, W: 15at%;

[0032] Adding Fe blocks with a purity of 3N5, Co blocks with a purity of 3N and Nb blocks with a purity of ≥99.5% into a smelting furnace, and atomizing the molten metal obtained by vacuum smelting under high-pressure argon atomization conditions of a temperature of 1650° C. and a pressure of 3.6 MPa to obtain FeCoNb alloy powder with a particle size of <150 mesh and an oxygen content of 350±10ppm;

[0033] Step 2, adding the FeCoNb alloy powder and W powder with a purity of 3N5 and a particle size of -325 mesh into a V-type powder mixer, filling with argon gas to prevent air from entering, mixing the powder for 25 hours, and taking out the FeCoNbW alloy powder after the powder mixing is completed;

[0034] The package is designed according to the size of the finished product. The package material is SUS304. High-temperature cotton is laid on the inner wall of the package. The FeCoNbW alloy powder is loaded into the package and compacted to ensure that the flatness of the mold is less than 1mm. After laying high-temperature cotton on the top of the powder, the package cover with a degassing port is welded to the outside of the package, and the degassing pipe is welded to the outlet. The package is leak-checked with a helium mass spectrometer. After the leak is checked, it is placed in a degassing furnace for heating and degassing. The molecular pump is used for degassing. The degassing temperature is 500℃. When the vacuum degree inside the package is less than 2×10 -3 After Pa, the degassing pipe near the package is clamped flat and the excess part is cut off to form a closed vacuum environment in the package;

[0035] Put the sealed package into the hot isostatic pressing furnace and start gradient hot isostatic pressing sintering:

[0036] Increase the pressure from cold state to 50MPa, and at the same time increase the temperature from room temperature to 750℃ at a rate of 10℃ / min, and calcine at this temperature and pressure for 60min, with natural pressure increase during the heating process;

[0037] The temperature was raised from 750°C to 1000°C at a rate of 5°C / min, and the pressure was increased during the heating process. When the temperature reached, the pressure was 115MPa. The sintering was carried out at a sintering temperature of 1000°C and a sintering pressure of 115MPa for 200min.

[0038] After sintering, the furnace is naturally depressurized and cooled to ≤100°C to obtain a FeCoNbW alloy target blank with a flatness of <1mm;

[0039] Due to the extremely high hardness of FeCoNbW alloy, CNC grinder is used to process the thickness, and wire cutting is used to cut the shape to the finished size. After that, it is cleaned, dried and packaged to form the final FeCoNbW alloy target.

[0040] Example 2

[0041] A hot isostatic pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the mass percentages of Fe: 10at%, Co: 65at%, Nb: 5at%, and W: 20at% to prepare FeCoNb alloy powder, which is then mixed with W powder; the remaining steps and parameters remain the same.

[0042] Example 3

[0043] A hot isostatic pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the mass percentages of Fe: 20at%, Co: 65at%, Nb: 5at%, and W: 10at% to prepare FeCoNb alloy powder, which is then mixed with W powder; the remaining steps and parameters remain the same.

[0044] Example 4

[0045] A hot isostatic pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the mass percentages of Fe: 20at%, Co: 55at%, Nb: 5at%, and W: 20at% to prepare FeCoNb alloy powder, which is then mixed with W powder; the remaining steps and parameters remain the same.

[0046] Example 5

[0047] A hot isostatic pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that the sintering temperature is replaced with 950° C., and the other steps and parameters remain the same.

[0048] Comparative Example 1

[0049] A hot isostatic pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that the sintering temperature is replaced with 900° C., and the other steps and parameters remain the same.

[0050] Comparative Example 2

[0051] A hot isostatic pressing preparation method for a FeCoNbW alloy target is different from that of Example 1 in that the sintering temperature is replaced with 1100° C., and the other steps and parameters remain the same.

[0052] Comparative Example 3

[0053] A hot isostatic pressing preparation method for a FeCoNbW alloy target, which is different from that of Example 1 in that a direct powder mixing method is used, i.e., Fe powder, Co powder, Nb powder and W powder are weighed according to the element mass percentages of Fe: 15 at%, Co: 65 at%, Nb: 5 at%, and W: 15 at%; four kinds of metal powders are added into a V-type powder mixer, filled with argon gas to prevent air from entering, and the powders are mixed for 25 hours, and after the powder mixing is completed, the FeCoNbW alloy powder is taken out;

[0054] The remaining steps and parameters remain the same.

[0055] The performance of the FeCoNbW alloy targets prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was tested:

[0056] Archimedes was used to measure the density of the target material;

[0057] The metallographic microscope was used for observation, and the intercept method was used to calculate the average grain size;

[0058] Test the magnetic permeability (PTF) according to ASTM F2086-01 standard;

[0059] Purity was tested using GDMS.

[0060] The test results are shown in Table 1:

[0061] Table 1

[0062]

[0063]

[0064] As can be seen from Table 1, by adjusting the ratio of the content of each element in the FeCoNbW alloy target material, Examples 1 to Example 5 prepare the FeCoNbW alloy target material with precise composition control, uniform composition distribution, high purity and high magnetic permeability, which is suitable for magnetron sputtering and has good soft magnetic properties; Comparing Example 1 with Comparative Example 1, the hot isostatic pressing sintering temperature of Comparative Example 1 is relatively low, resulting in poor density of the alloy target material, but the magnetic permeability remains at a good level; Comparing Example 1 with Comparative Example 2, the temperature in Comparative Example 2 is too high, and although the density is good, the grains grow abnormally, resulting in low magnetic permeability; Comparing Example 1 with Comparative Example 3, the alloy target material prepared by directly mixing the alloy powders in 4 has good properties such as density and purity, but poor magnetic permeability.

[0065] The present application limits the powder mixing method of the alloy target material and adopts a gradient hot isostatic pressing sintering method to help form a uniform whole inside the powder and avoid cracking of the target material. Uniform isostatic pressure is applied to the powder body around the powder by uniform pressure, so that the target material undergoes plastic deformation and crystallization at high temperature, thereby achieving material densification and strengthening, and effectively improving the yield rate of the FeCoNbW alloy target material.

[0066] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hot isostatic pressing method for preparing a FeCoNbW alloy target, characterized in that: The following steps are involved: Step 1, vacuum melting Fe blocks, Co blocks, and Nb blocks and then atomizing them to obtain FeCoNb alloy powder; Step 2, FeCoNb alloy powder and W powder are mixed to obtain FeCoNbW alloy powder, and the powder is subjected to encapsulation, molding, degassing, gradient hot isostatic pressing sintering, and machining in sequence to obtain FeCoNbW alloy target; The specific sintering process of the gradient hot isostatic pressing sintering is as follows: First temperature increase and pressure increase: pressurize from cold state to 45-55MPa, and at the same time heat from room temperature to 700-800℃ at the first heating rate, keep the temperature and pressure and calcine for 50-70min, and naturally increase the pressure during the temperature increase process; Second heating and pressurizing: heating from 700-800°C to 950-1050°C at the second heating rate, pressurizing at the same time during the heating process, making the pressure ≥110MPa when the temperature reaches the target, and calcining at the temperature and pressure for 180-240min; The third step is to reduce temperature and pressure: after calcination, the temperature and pressure will naturally decrease to ≤100℃.

2. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The mass percentage of elements in the FeCoNbW alloy target is Fe: 10-20at%, Nb: 4-6at%, W: 10-20at%, and the balance is Co.

3. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The atomization pressure of gas atomization is 3.6MPa, the atomization temperature is 1650°C, and the atomization gas is argon.

4. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The oxygen content of the FeCoNb alloy powder is ≤400ppm and the particle size is <150 mesh.

5. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The purity of W powder is ≥3N5 and the particle size is -325 mesh.

6. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The powder is mixed using a V-type powder mixer, filled with argon gas for protection, and the mixing time is 20-30 hours.

7. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The stainless steel type used for the package is SUS304 or SUS316L, and the flatness of the mold is less than 1mm.

8. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The degassing temperature is 400-600℃, and the vacuum degree in the package is less than 2×10 -3 Pa.

9. The hot isostatic pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The first heating rate is 9-11℃ / min, and the second heating rate is 4-6℃ / min.

10. A FeCoNbW alloy target, characterized in that: Prepared by the preparation method according to any one of claims 1 to claim 9.

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