A FeCoNbW alloy target and its hot isostatic pressing preparation method

Abstract

This invention discloses an FeCoNbW alloy target and its preparation method using hot isostatic pressing, belonging to the field of magnetic storage target manufacturing technology. The method includes the following steps: vacuum melting of Fe, Co, and Nb blocks followed by gas atomization to obtain FeCoNb alloy powder; mixing the FeCoNb alloy powder with W powder and then sequentially subjecting the mixture to encapsulation, molding, degassing, gradient hot isostatic pressing sintering, and machining to obtain the FeCoNbW alloy target. By combining FeCoNb alloy powder with W powder to form a mixed powder of the target composition, the FeCoNb alloy powder, due to the formation of a metallic alloy among its components, can demagnetize and improve the final magnetic permeability of the target. Then, the target blank is sintered using gradient hot isostatic pressing, solving the problems of uneven composition, target blank cracking during conventional plastic deformation, and low magnetic permeability, effectively improving the yield of the FeCoNbW alloy target.

Description

Technical Field

[0001] This invention belongs to the field of magnetic storage target manufacturing technology, specifically relating to an FeCoNbW alloy target and its hot isostatic pressing preparation method. Background Technology

[0002] Fe-Co alloys are high-performance soft magnetic materials with extremely high saturation magnetic flux density Bs (2.4T) and Curie temperature (980-1100℃), making them suitable for manufacturing aerospace electrical components (micromotors, electromagnets, relays, etc.) that require lightweight, small size, and high operating temperatures. Furthermore, they possess a large saturation magnetostriction coefficient λs, which can be used to fabricate magnetostrictive transducers and various magnetic recording devices, such as novel sensors, magnetic recording readout heads, and filters. Doping Fe-Co alloys with small amounts of Nb can react with impurities in the alloy to improve its soft magnetic properties; on the other hand, it can form Co-Nb localized disorder regions with Co, refining the grain size.

[0003] To further improve the magnetic properties of FeCoNb alloys, introducing tungsten (W) into the alloy system can enhance the hardness and wear resistance of soft magnetic alloys while maintaining good magnetic properties. There are generally two conventional methods for preparing sputtering targets: one is to prepare them by melting and casting followed by forging, rolling, and heat treatment; this method is suitable for metals or alloys with good plastic deformation capabilities. The other method is to prepare them through powder metallurgy, which is suitable for difficult-to-deform metals or high-temperature alloys. For FeCoNbW alloys, the addition of W, which has an extremely high melting point and hardness, increases the alloy's hardness but reduces its plastic deformation capability. Therefore, FeCoNbW alloy sputtering targets are difficult to prepare through melting and plastic deformation. Furthermore, existing technologies do not disclose methods for preparing FeCoNbW alloy sputtering targets. Summary of the Invention

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

[0005] The objective of this invention can be achieved through the following technical solutions:

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

[0007] Step 1: After vacuum melting of Fe blocks, Co blocks, and Nb blocks, the mixture is atomized to obtain FeCoNb alloy powder;

[0008] Step 2: Mix FeCoNb alloy powder with W powder to obtain FeCoNbW alloy powder, and then process it sequentially through cladding, molding, degassing, gradient hot isostatic pressing sintering, and machining to obtain FeCoNbW alloy target material.

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

[0010] First heating 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, hold at temperature and pressure for 50-70min, and pressurize naturally during the heating process;

[0011] Second heating and pressurization: Pressurization is simultaneously increased during the heating process. The temperature is increased from 700-800℃ to 950-1050℃ at the second heating rate. When the temperature is reached, the pressure is ≥110MPa. The calcination is carried out for 180-240 minutes under the conditions of sintering temperature of 950-1050℃ and sintering pressure ≥110MPa.

[0012] Third, cooling and depressurization: After calcination, the furnace is naturally depressurized and cooled to ≤100℃.

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

[0014] Furthermore, the atomization pressure of the gas atomization is 3.6 MPa, the atomization temperature is 1650℃, and the atomizing 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, a V-type powder mixer is used for powder mixing, and argon gas is used for protection to prevent air from entering. The powder mixing time is 20-30 hours.

[0018] Furthermore, the casing is made of stainless steel of type SUS304 or SUS316L, the flatness of the mold is <1mm, and high-temperature cotton is used to separate the FeCoNbW alloy powder from the casing to prevent Fe and C from reacting.

[0019] Furthermore, the degassing temperature is 400-600℃, and the vacuum degree inside the casing after degassing is <2×10⁻⁶. -3 Pa.

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

[0021] Furthermore, the machining process involves using a CNC grinding machine to process the thickness, and then using a slow wire EDM to cut the shape to the finished product size. After that, the product is cleaned, dried, and packaged.

[0022] Secondly, an FeCoNbW alloy target material is prepared by the above-mentioned hot isostatic pressing method.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This invention provides a hot isostatic pressing (HIP) method for preparing FeCoNbW alloy targets. This method uses FeCoNb alloy powder combined with W powder to form a mixed powder with the target composition. Because the FeCoNb alloy powder forms a metallic alloy with its components, it can demagnetize and improve the final magnetic permeability of the target material. Then, the target blank is sintered using gradient HIP, solving the problems of uneven composition, cracking of the target blank during conventional plastic deformation, and low magnetic permeability, thereby effectively improving the yield of FeCoNbW alloy targets. The prepared target material has a composition control accuracy of ±0.2 at%, with deviations of less than 0.5% at various locations. It has uniform and fine grains (<50 μm), no internal defects, and a smooth surface. According to ASTM F2086-01 standard, the magnetic permeability is ≥30%, meeting the application requirements.

[0025] 2. The alloy target material prepared by the method of this invention has a purity ≥3N5 (99.95%) and a density ≥99%. It is composed of the following elements by atomic percentage: Fe: 10-20 at%; W: 10-20 at%; Nb: 4-6 at%, with the balance being Co. This method offers advantages such as precise control of the finished product composition, uniform composition distribution without segregation or inclusions, fine and uniform grains, high purity, high density, high magnetic permeability, and uniformity throughout. This target material is suitable for magnetron sputtering and exhibits good soft magnetism. Attached Figure Description

[0026] The present invention will now be further described with reference to the accompanying drawings.

[0027] Figure 1 This is a schematic diagram of the process flow for the hot isostatic pressing preparation of a FeCoNbW alloy target material according to the present invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] Please see Figure 1 A hot isostatic pressing method for preparing FeCoNbW alloy targets includes the following steps:

[0031] Step 1: Weigh out Fe blocks, Co blocks, Nb blocks and W powder according to the element mass percentages of Fe: 15 at%, Co: 65 at%, Nb: 5 at%, W: 15 at%.

[0032] Fe blocks with a purity of 3N5, Co blocks with a purity of 3N, and Nb blocks with a purity of ≥99.5% were added to a melting furnace. The molten metal obtained by vacuum melting was atomized under high-pressure argon atomization conditions at a temperature of 1650℃ and a pressure of 3.6MPa to obtain FeCoNb alloy powder with a particle size of <150 mesh and an oxygen content of 350±10ppm.

[0033] Step 2: Add 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, fill it with argon gas to prevent air from entering, mix for 25 hours, and take out the FeCoNbW alloy powder after the mixing is completed.

[0034] The casing was designed according to the finished product dimensions, using SUS304 material. High-temperature cotton was laid on the inner wall of the casing. FeCoNbW alloy powder was then loaded into the casing and compacted to ensure a flatness of <1mm. After laying high-temperature cotton on top of the powder, a casing cover plate with a degassing port was welded to the outside of the casing, and the degassing pipe was welded to the outlet. A helium mass spectrometer was used to check for leaks. After leak detection, the casing was placed in a degassing furnace and heated to 500℃ using a molecular pump for degassing, until the internal vacuum degree of the casing was <2×10⁻⁶. -3 After Pa, the degassing tube near the sheath is flattened and the excess part is cut off to create a sealed vacuum environment inside the sheath.

[0035] The sealed sizing is placed into a hot isostatic pressing furnace, and gradient hot isostatic pressing sintering begins:

[0036] The pressure was increased from cold to 50 MPa, and the temperature was increased from room temperature to 750°C at a rate of 10°C / min. The temperature and pressure were maintained for 60 minutes, and the pressure was increased naturally during the heating process.

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

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

[0039] Due to the extremely high hardness of FeCoNbW alloy, the thickness is processed using a CNC grinding machine, and the shape is cut to the finished size using a slow wire EDM. After that, it is cleaned, dried and packaged to form the final finished FeCoNbW alloy target material.

[0040] Example 2

[0041] A hot isostatic pressing method for preparing FeCoNbW alloy targets differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the mass percentages of Fe: 10 at%, Co: 65 at%, Nb: 5 at%, and W: 20 at% 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 method for preparing FeCoNbW alloy targets differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the mass percentages of Fe: 20 at%, Co: 65 at%, Nb: 5 at%, and W: 10 at% 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 method for preparing FeCoNbW alloy targets differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the mass percentages of Fe: 20 at%, Co: 55 at%, Nb: 5 at%, and W: 20 at% 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 method for preparing FeCoNbW alloy targets differs from Example 1 in that the sintering temperature is replaced with 950℃, while the remaining steps and parameters remain the same.

[0048] Comparative Example 1

[0049] A hot isostatic pressing method for preparing FeCoNbW alloy targets differs from Example 1 in that the sintering temperature is replaced with 900℃, while the remaining steps and parameters remain the same.

[0050] Comparative Example 2

[0051] A hot isostatic pressing method for preparing FeCoNbW alloy targets differs from Example 1 in that the sintering temperature is replaced with 1100℃, while the remaining steps and parameters remain the same.

[0052] Comparative Example 3

[0053] A hot isostatic pressing method for preparing FeCoNbW alloy targets differs from Example 1 in that the powder mixing method is direct powder mixing. Specifically, Fe powder, Co powder, Nb powder, and W powder are weighed according to the elemental mass percentages of Fe: 15 at%, Co: 65 at%, Nb: 5 at%, and W: 15 at%. The four metal powders are added to a V-type powder mixer, and argon gas is introduced to prevent air from entering. The powder is mixed for 25 hours, and the FeCoNbW alloy powder is removed after the mixing is completed.

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

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

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

[0057] The average grain size was calculated using the intercept method after observation with a metallographic microscope.

[0058] The permeability (PTF) was tested 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 shown in Table 1, by adjusting the proportions of each element in the FeCoNbW alloy target material, Examples 1-5 resulted in FeCoNbW alloy target materials with precise composition control, uniform composition distribution, high purity, and high magnetic permeability, making them suitable for magnetron sputtering and exhibiting good soft magnetism. Compared to Example 1 and Comparative Example 1, Comparative Example 1 had a lower hot isostatic pressing sintering temperature, resulting in poorer density of the alloy target material, but maintaining a good level of magnetic permeability. Compared to Example 1 and Comparative Example 2, Comparative Example 2 had an excessively high temperature, resulting in good density but abnormal grain growth and lower magnetic permeability. Compared to Example 1 and Comparative Example 3, the alloy target material prepared by directly mixing the alloy powders from Example 4 had good density, purity, and other properties, but poor magnetic permeability.

[0065] This application helps to form a uniform whole inside the powder by limiting the powder mixing method of the alloy target and adopting gradient hot isostatic pressing sintering, thus avoiding cracking of the target. By applying uniform isostatic pressure to the powder, the target undergoes plastic deformation and crystallization at high temperature, thereby achieving material densification and strengthening, and effectively improving the yield of FeCoNbW alloy target.

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

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

Claims

1. A method for preparing FeCoNbW alloy target material by hot isostatic pressing, characterized in that, Includes the following steps: Step 1: After vacuum melting of Fe blocks, Co blocks, and Nb blocks, the mixture is atomized to obtain FeCoNb alloy powder; Step 2: Mix FeCoNb alloy powder with W powder to obtain FeCoNbW alloy powder, and then process it sequentially through cladding, molding, degassing, gradient hot isostatic pressing sintering, and machining to obtain FeCoNbW alloy target material. The specific sintering process of gradient hot isostatic pressing sintering is as follows: First heating and pressurization: pressurize from cold state to 45-55MPa, and simultaneously heat from room temperature to 700-800℃ at the first heating rate, hold the temperature and pressure for 50-70 minutes, and pressurize naturally during the heating process; Second heating and pressurization: Heat from 700-800℃ to 950-1050℃ at the second heating rate, and pressurize at the same time during the heating process. When the temperature is reached, the pressure is ≥110MPa. Hold the temperature and pressure for calcination for 180-240min. Third cooling and depressurization: After calcination, the furnace is naturally depressurized and cooled to ≤100℃; The mass percentage of elements in the FeCoNbW alloy sputtering material is Fe: 10-20 at%, Nb: 4-6 at%, W: 10-20 at%, with the balance being Co; The first heating rate is 9-11℃ / min, and the second heating rate is 4-6℃ / min.

2. The hot isostatic pressing method for preparing FeCoNbW alloy target material according to claim 1, characterized in that, The atomization pressure of the gas atomization is 3.6 MPa, the atomization temperature is 1650℃, and the atomizing gas is argon.

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

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

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

6. The hot isostatic pressing method for preparing FeCoNbW alloy target material according to claim 1, characterized in that, The casing is made of stainless steel of type SUS304 or SUS316L, and the flatness of the mold is <1mm.

7. The hot isostatic pressing method for preparing FeCoNbW alloy target material according to claim 1, characterized in that, The degassing temperature is 400-600℃, and the degassing is performed until the vacuum degree inside the casing is <2×10⁻⁶. -3 Pa.

8. A FeCoNbW alloy target material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

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