A method for preparing a ni-fe-w-al alloy target material by a hot isostatic pressing method, and a ni-fe-w-al alloy target material

Abstract

The application belongs to the field of magnetic storage target material manufacturing, and discloses a method for preparing a NiFeWAl alloy target material by a hot isostatic pressing method, and specifically comprises the following steps: step 1: NiFeWAl alloy is prepared into NiFeWAl alloy powder by a vacuum atomization method, the powder is loaded into a package, the package is welded after the powder is flattened, and then degassing and air sealing operations are performed; step 2: the package obtained in step 1 is subjected to hot isostatic pressing sintering operation, and the package is removed after sintering is completed to obtain a rough target blank; step 3: the rough target blank is machined to obtain a finished NiFeWAl alloy target material; the NiFeWAl alloy target material contains Ni atoms, Fe atoms, W atoms and Al atoms, the atomic percentage of the Ni atoms is 65% to 75%, and the atomic percentage of the Fe atoms is 20% to 30%. Meanwhile, a NiFeWAl alloy target material is also disclosed.

Description

Technical Field

[0001] This invention belongs to the field of magnetic storage target manufacturing, and discloses a method for preparing NiFeWAl alloy targets by hot isostatic pressing and the NiFeWAl alloy targets themselves. Background Technology

[0002] Magnetron sputtering is a widely used technology in fields such as semiconductor integrated circuits and solar photovoltaics. It utilizes ions generated by an ion source, which are accelerated and focused in a vacuum to form an ion beam that bombards a solid surface. The ions and the atoms on the solid surface exchange kinetic energy, ultimately causing the atoms on the solid surface to leave the solid and deposit on the substrate to form a thin film. The solid being bombarded is called the sputtering target, which is one of the most crucial basic materials.

[0003] With the development of magnetic recording thin film technology, the required sputtering targets are also constantly changing. In the existing technology, there are generally two conventional methods for preparing targets. One is to prepare them by forging, rolling and heat treatment after melting and casting. This method is suitable for metals or alloys with good plastic deformation ability. For alloys with poor deformation ability, there is often a risk of cracking during the forging process. The other method is to prepare them by powder metallurgy. This method is suitable for metals that are difficult to deform or high-temperature alloys.

[0004] NiFeWAl alloy sputtering target is a brand-new sputtering target developed by our company. It is used in the field of magnetic storage. It contains W and Al elements. The addition of W increases the hardness of the alloy and reduces its plastic deformation ability. At the same time, Al has a low melting point and low content, which can easily lead to uneven alloy composition and poor performance of the final product.

[0005] Therefore, the technical problem that needs to be solved in this case is: how to prepare high-performance NiFeWAl alloy targets. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing NiFeWAl alloy targets by hot isostatic pressing. By precisely controlling the temperature and pressure changes during the hot isostatic pressing sintering process, the problem of uneven component distribution caused by the large difference in melting points of the alloy components is solved, thereby producing high-performance NiFeWAl alloy targets.

[0007] Meanwhile, the present invention also discloses a NiFeWAl alloy target.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing NiFeWAl alloy targets by hot isostatic pressing specifically includes the following steps:

[0010] Step 1: NiFeWAl alloy is prepared into NiFeWAl alloy powder by vacuum atomization (VGA), the powder is loaded into a sleeve, the powder is leveled and the sleeve is welded, and then degassing and gas sealing operations are performed.

[0011] Step 2: Perform hot isostatic pressing sintering on the cladding obtained in Step 1. After sintering, remove the cladding to obtain the blank target blank.

[0012] Step 3: Machin the blank target to obtain the finished NiFeWAl alloy target material;

[0013] The NiFeWAl alloy target contains Ni atoms, Fe atoms, W atoms, and Al atoms, with the molar percentage of Ni atoms being 65% to 75% and the molar percentage of Fe atoms being 20% ​​to 30%.

[0014] The NiFeWAl alloy powder used in this invention utilizes Al to optimize the magnetic anisotropy of the alloy target, thus enhancing magnetic recording efficiency. W, on the other hand, improves the hardness and wear resistance of the alloy target. However, Al has a relatively low melting point of around 660°C, while W has a melting point as high as around 3400°C. The difference in melting points is significant. If sintering is performed directly at high temperatures, Al will dissolve first, easily causing component segregation and resulting in a significant reduction in the performance of the final alloy target. In this invention, it was found that sintering the alloy powder at around 600°C pre-alloys the powder, thereby increasing the melting point of Al. During subsequent high-temperature sintering, the composition distribution remains uniform, allowing the final alloy target to maintain both high wear resistance and excellent magnetic anisotropy.

[0015] Preferably, the molar percentage of Ni atoms is 68% to 75%, and the molar percentage of Fe atoms is 24% to 30%.

[0016] Preferably, the molar percentage ratio of Ni, Fe, W and Al in the alloy target is 65-75:20-30:4-6:1-2.

[0017] More preferably, the molar percentage ratio of Ni, Fe, W and Al in the alloy target is 68-75:24-30:4-6:1-2.

[0018] Preferably, the oxygen content in the alloy powder described in step 1 is ≤400ppm, and the powder particle size is ≤100um;

[0019] Preferably, the vacuum degree of the degassing and sealing operation in step 1 is ≤2*E-3Pa.

[0020] Preferably, the hot isostatic pressing sintering operation in step 2 is as follows: the temperature is increased from room temperature to 600℃~610℃ at a heating rate of 10℃ / min, and the pressure is naturally increased to 45MPa~55MPa during the heating process, and the temperature and pressure are held for 58min~62min; then the temperature is increased to 850℃~950℃ at a heating rate of 5℃ / min, and the pressure is increased to ≥110MPa when the temperature is reached, and then the temperature and pressure are held for 180min~240min, and the pressure and temperature are naturally reduced with the furnace after the end.

[0021] More preferably, the hot isostatic pressing sintering operation is as follows: the temperature is increased from room temperature to 605°C at a heating rate of 10°C / min, and the pressure is naturally increased to 50MPa during the heating process, and the temperature and pressure are maintained for 60min; then the temperature is increased to 900°C to 950°C at a heating rate of 5°C / min, and the pressure is increased to ≥110MPa when the temperature is reached, and then the temperature and pressure are maintained for 210min to 240min, and after the end, the pressure and temperature are naturally reduced with the furnace.

[0022] In addition, a NiFeWAl alloy target material is disclosed, which is prepared by the method described above.

[0023] The beneficial effects of this invention are:

[0024] Pre-alloying is performed using Ni, Fe, W, and NiAl blocks in a vacuum melting process to eliminate some of the magnetism of Ni and Fe. Then, the alloy powder is prepared by gas atomization to reduce the oxygen content of the powder. The alloy powder is then pre-sintered using a reheat isostatic pressing method to pre-alloy the powder, thereby increasing the melting point of Al. During subsequent high-temperature sintering, the composition distribution remains uniform, allowing the finished alloy target to maintain excellent magnetic anisotropy while possessing high wear resistance. The final product is a NiFeWAl alloy target with precise composition control, uniform composition distribution, no segregation or inclusions, fine and uniform grains, high purity, high density, high magnetic permeability, and uniformity throughout. Attached Figure Description

[0025] Figure 1 This is a flowchart of the process of the present invention. Detailed Implementation

[0026] The technical solution 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. It should be noted that, where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] Example 1

[0028] Step 1: NiFeWAl alloy with a molar percentage of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into NiFeWAl alloy powder using vacuum atomization (VGA). The powder particle size is 100 μm, and the oxygen content in the powder is ≤400 ppm. The powder is loaded into a sleeve, and after the powder is leveled, the sleeve is welded. Then, the sleeve is placed in a degassing furnace and heated. Degassing is performed using a molecular pump. After the vacuum degree reaches 2*E-3 Pa, the air is sealed to maintain a vacuum state inside the sleeve.

[0029] The specific operation of the vacuum atomization method is as follows: Select a NiAl alloy (50:50) that can be directly purchased from the market, and then put the NiAl alloy block, Ni block, Fe block and W block prepared according to the target ratio into the VGA equipment. Melt in a vacuum at 1500℃ in an alumina crucible and hold for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 150-mesh sieve to obtain NiFeWAl alloy powder.

[0030] Step 2: Place the degassed casing into a hot isostatic pressing furnace, and heat it at a rate of 10℃ / min from room temperature to 605℃, naturally pressurizing it to 50MPa during the heating process, and holding it at that temperature and pressure for 60min. Then, heat it to 900℃ at a rate of 5℃ / min, simultaneously increasing the pressure to ≥110MPa upon reaching the desired temperature, and then hold it at that temperature and pressure for 210min. After the process, allow the furnace to naturally depressurize and cool down. After sintering, remove the casing to obtain the raw target blank.

[0031] Step 3: Machining the blank target blank involves using a CNC grinder to process the thickness and a CNC lathe to process the sides. After cleaning, drying, and packaging, the finished NiFeWAl alloy target material is obtained.

[0032] The above process flow is for reference. Figure 1

[0033] Example 2

[0034] Step 1: NiFeWAl alloy with a molar percentage of 75% Ni, 20% Fe, 4% W, and 1% Al is prepared into NiFeWAl alloy powder by vacuum atomization (VGA). The powder particle size is 100 μm, and the oxygen content in the powder is ≤400 ppm. The powder is loaded into a sleeve, and after the powder is leveled, the sleeve is welded. Then, the sleeve is placed in a degassing furnace and heated. Degassing is performed using a molecular pump. After the vacuum degree reaches 2*E-3 Pa, the air is sealed to maintain a vacuum state inside the sleeve.

[0035] The specific operation of the vacuum atomization method is as follows: Select a NiAl alloy (50:50) that can be directly purchased from the market, and then put the NiAl alloy block, Ni block, Fe block and W block prepared according to the target ratio into the VGA equipment. Melt in a vacuum at 1500℃ in an alumina crucible and hold for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 150-mesh sieve to obtain NiFeWAl alloy powder.

[0036] Step 2: Place the degassed casing into a hot isostatic pressing furnace, and heat it at a rate of 10℃ / min from room temperature to 605℃, naturally pressurizing it to 50MPa during the heating process, and holding it at that temperature and pressure for 60min. Then, heat it to 900℃ at a rate of 5℃ / min, simultaneously increasing the pressure to ≥110MPa upon reaching the desired temperature, and then hold it at that temperature and pressure for 210min. After the process, allow the furnace to naturally depressurize and cool down. After sintering, remove the casing to obtain the raw target blank.

[0037] Step 3: Machining the blank target blank involves using a CNC grinder to process the thickness and a CNC lathe to process the sides. After cleaning, drying, and packaging, the finished NiFeWAl alloy target material is obtained.

[0038] Example 3

[0039] Step 1: NiFeWAl alloy with a molar percentage of 65% Ni, 30% Fe, 4% W, and 1% Al is prepared into NiFeWAl alloy powder by vacuum atomization (VGA). The powder particle size is 100 μm, and the oxygen content in the powder is ≤400 ppm. The powder is loaded into a sleeve, and after the powder is leveled, the sleeve is welded. Then, the sleeve is placed in a degassing furnace and heated. Degassing is performed using a molecular pump. After the vacuum degree reaches 2*E-3 Pa, the air is sealed to maintain a vacuum state inside the sleeve.

[0040] The specific operation of the vacuum atomization method is as follows: Select a NiAl alloy (50:50) that can be directly purchased from the market, and then put the NiAl alloy block, Ni block, Fe block and W block prepared according to the target ratio into the VGA equipment. Melt in a vacuum at 1500℃ in an alumina crucible and hold for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 150-mesh sieve to obtain NiFeWAl alloy powder.

[0041] Step 2: Place the degassed casing into a hot isostatic pressing furnace, and heat it at a rate of 10℃ / min from room temperature to 605℃, naturally pressurizing it to 50MPa during the heating process, and holding it at that temperature and pressure for 60min. Then, heat it to 900℃ at a rate of 5℃ / min, simultaneously increasing the pressure to ≥110MPa upon reaching the desired temperature, and then hold it at that temperature and pressure for 210min. After the process, allow the furnace to naturally depressurize and cool down. After sintering, remove the casing to obtain the raw target blank.

[0042] Step 3: Machining the blank target blank involves using a CNC grinder to process the thickness and a CNC lathe to process the sides. After cleaning, drying, and packaging, the finished NiFeWAl alloy target material is obtained.

[0043] Example 4

[0044] Step 1: NiFeWAl alloy with a molar percentage composition of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into NiFeWAl alloy powder by vacuum atomization (VGA). The powder particle size is 100 μm, and the oxygen content in the powder is ≤400 ppm. The powder is loaded into a sleeve, and after the powder is leveled, the sleeve is welded. Then, the sleeve is placed in a degassing furnace and heated. Degassing is performed using a molecular pump. After the vacuum degree reaches 2*E-3 Pa, the air is sealed to maintain a vacuum state inside the sleeve.

[0045] The specific operation of the vacuum atomization method is as follows: Select a NiAl alloy (50:50) that can be directly purchased from the market, and then put the NiAl alloy block, Ni block, Fe block and W block prepared according to the target ratio into the VGA equipment. Melt in a vacuum at 1500℃ in an alumina crucible and hold for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 150-mesh sieve to obtain NiFeWAl alloy powder.

[0046] Step 2: Place the degassed casing into a hot isostatic pressing furnace, and heat it at a rate of 10℃ / min from room temperature to 610℃, naturally pressurizing it to 55MPa during the heating process, holding it at that temperature and pressure for 58 minutes. Then, heat it to 950℃ at a rate of 5℃ / min, simultaneously increasing the pressure to ≥110MPa upon reaching the desired temperature, and then hold it at that temperature and pressure for 180 minutes. After the process, allow the furnace to naturally depressurize and cool down. After sintering, remove the casing to obtain the raw target blank.

[0047] Step 3: Machining the blank target blank involves using a CNC grinder to process the thickness and a CNC lathe to process the sides. After cleaning, drying, and packaging, the finished NiFeWAl alloy target material is obtained.

[0048] Example 5

[0049] Step 1: NiFeWAl alloy with a molar percentage composition of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into NiFeWAl alloy powder by vacuum atomization (VGA). The powder particle size is 100 μm, and the oxygen content in the powder is ≤400 ppm. The powder is loaded into a sleeve, and after the powder is leveled, the sleeve is welded. Then, the sleeve is placed in a degassing furnace and heated. Degassing is performed using a molecular pump. After the vacuum degree reaches 2E-3 Pa, the air is sealed to maintain a vacuum state inside the sleeve.

[0050] The specific operation of the vacuum atomization method is as follows: Select a commercially available NiAl alloy (50:50), and then put the NiAl alloy block, Ni block, Fe block, and W block prepared according to the target ratio into the VGA equipment. Melt them in a vacuum at 1500℃ in an alumina crucible and hold for 20 min to 30 min. Then perform argon atomization at an argon pressure of 3 MPa to 4 MPa. The resulting powder is sieved through a 150-mesh sieve to obtain NiFeWAl alloy powder.

[0051] Step 2: Place the degassed casing into a hot isostatic pressing furnace, and heat it from room temperature to 600℃ at a rate of 10℃ / min. During the heating process, naturally pressurize to 45MPa and hold at that temperature and pressure for 62 minutes. Then, heat it to 850℃ at a rate of 5℃ / min, simultaneously increasing the pressure to ≥110MPa upon reaching the desired temperature. Hold at that temperature and pressure for 240 minutes. After the process, allow the furnace to naturally depressurize and cool down. After sintering, remove the casing to obtain the raw target blank.

[0052] Step 3: Machining the blank target blank involves using a CNC grinder to process the thickness and a CNC lathe to process the sides. After cleaning, drying, and packaging, the finished NiFeWAl alloy target material is obtained.

[0053] Example 6

[0054] The specific experimental steps are largely the same as in Example 1. The difference is that in step 2, the specific process of hot isostatic pressing sintering is as follows: the temperature is increased from room temperature to 850°C at a heating rate of 5°C / min. When the temperature is reached, the pressure is increased to ≥110MPa. Then, the temperature and pressure are maintained for 180 to 240 minutes. After the end, the pressure and temperature are naturally reduced with the furnace.

[0055] Comparative Example 1

[0056] The specific experimental steps are largely the same as in Example 1. The difference is that in step 1, Ni powder, Fe powder, W powder, and Al powder are used directly in place of alloy powder according to the molar percentage. The particle size of Ni powder, Fe powder, W powder, and Al powder is controlled to be below 100 μm, with the average particle size of Ni powder being 100 μm, the average particle size of Fe powder being 100 μm, the average particle size of W powder being 45 μm, and the average particle size of Al powder being 45 μm.

[0057] Comparative Example 2:

[0058] The specific experimental steps are largely the same as in Example 1, except that step 2 involves the following process: The degassed casing is placed in a hot isostatic pressing furnace, and the furnace is heated at a rate of 10°C / min from room temperature to 605°C. During the heating process, the pressure is naturally increased to 50 MPa, and the temperature and pressure are maintained for 60 minutes. Then, the temperature is increased to 800°C at a rate of 5°C / min, and the pressure is simultaneously increased to ≥110 MPa upon reaching the desired temperature. This pressure is then maintained for 210 minutes, after which the furnace is allowed to naturally depressurize and cool down. After sintering, the casing is removed to obtain the raw target blank.

[0059] Comparative Example 3:

[0060] The specific experimental steps are largely the same as in Example 1, except that step 2 involves the following process: The degassed casing is placed in a hot isostatic pressing furnace, and the furnace is heated at a rate of 10°C / min from room temperature to 605°C. During the heating process, the pressure is naturally increased to 50 MPa, and the temperature and pressure are maintained for 60 minutes. Then, the temperature is increased to 1000°C at a rate of 5°C / min, and the pressure is simultaneously increased to ≥110 MPa upon reaching the desired temperature. This pressure is then maintained for 210 minutes, after which the furnace is allowed to naturally depressurize and cool down. After sintering, the casing is removed to obtain the raw target blank.

[0061] Comparative Example 4:

[0062] The specific experimental steps are largely the same as in Example 1, except that step 2 involves the following process: The degassed casing is placed in a hot isostatic pressing furnace, and the furnace is heated at a rate of 10°C / min from room temperature to 605°C. During the heating process, the pressure is naturally increased to 50 MPa, and the temperature and pressure are maintained for 60 minutes. Then, the temperature is increased to 800°C at a rate of 5°C / min, and the pressure is simultaneously increased to 100 MPa upon reaching the desired temperature. This pressure is then maintained for 210 minutes, after which the furnace is allowed to naturally depressurize and cool down. After sintering, the casing is removed to obtain the raw target blank.

[0063] Performance testing

[0064] The samples prepared in each embodiment and comparative example were tested for the following items: purity, density, average grain size, magnetic permeability, and appearance.

[0065] The density of the target material was measured using the Archimedes displacement method.

[0066] The average grain size was calculated using the intercept method after observation with a metallographic microscope.

[0067] The permeability (PTF) was tested according to ASTM F2086-01 standard.

[0068] Purity was tested using GDMS.

[0069] The specific test results are shown in Table 1 below;

[0070] Table 1 Performance Data of Alloy Targets

[0071]

[0072]

[0073] Conclusion Analysis

[0074] As can be seen from the data in Examples 1 to 6, the NiFeWAl alloy targets with different component contents prepared by the technical solution of the present invention all have excellent performance, among which the most important magnetic permeability is above 25%, and Example 1 is even as high as 29%.

[0075] A comparison of the data from Comparative Example 1 and Example 1 shows that when Comparative Example 1 used Ni powder, Fe powder, W powder, and Al powder instead of alloy powder as raw materials, the magnetic permeability of its product, NiFeWAl alloy target, was very low, only 8%. The main reason is that Ni powder, Fe powder, W powder, and Al powder have a high oxygen content, which cannot be eliminated during the sintering process, resulting in an excessively high oxygen content in the final product, thus causing a low magnetic permeability. The present invention can solve this problem by using alloy powder.

[0076] Comparative Example 2, based on Example 1, reduced the sintering temperature in step 2 to 800°C, which is lower than the range of 850°C to 950°C in the technical solution of this invention. This resulted in insufficient fusion of the alloy powder and poor density and magnetic permeability of the final product.

[0077] Comparative Example 3, based on Example 1, increased the sintering temperature in step 2 to 1000°C, which also exceeded the range. The excessively high temperature caused excessive grain growth in the alloy, with an average grain size of 80 μm. The excessively large grains would hinder the transmission of the magnetic field, resulting in a decrease in the magnetic permeability of the finished target material.

[0078] Comparative Example 4, based on Example 1, reduced the sintering pressure in step 2 to 100 MPa. Due to insufficient pressure, the alloy powder could not be tightly fused together, resulting in poor density and magnetic permeability of the final product.

[0079] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing NiFeWAl alloy targets by hot isostatic pressing, characterized in that, Specifically, the following steps are included: Step 1: NiFeWAl alloy is prepared into NiFeWAl alloy powder by vacuum atomization. The powder is loaded into a sleeve. After the powder is leveled, the sleeve is welded and then degassing and gas sealing operations are performed. Step 2: Perform hot isostatic pressing sintering on the cladding obtained in Step 1. After sintering, remove the cladding to obtain the blank target blank. Step 3: Machin the blank target to obtain the finished NiFeWAl alloy target material; The NiFeWAl alloy target contains Ni atoms, Fe atoms, W atoms, and Al atoms, and the molar percentage ratio of Ni, Fe, W, and Al in the alloy target is 65~75:20~30:4~6:1~2. The hot isostatic pressing sintering operation described in step 2 is as follows: the temperature is increased from room temperature to 600℃~610℃ at a heating rate of 10℃ / min, and the pressure is naturally increased to 45MPa~55MPa during the heating process, and the temperature and pressure are held for 58min~62min; then the temperature is increased to 850℃~950℃ at a heating rate of 5℃ / min, and the pressure is increased to ≥110MPa when the temperature is reached, and then the temperature and pressure are held for 180min~240min, and the pressure and temperature are naturally reduced with the furnace after the operation is completed.

2. The preparation method according to claim 1, characterized in that, The molar percentage ratio of Ni, Fe, W and Al in the alloy target is 68~75:24~30:4~6:1~2.

3. The preparation method according to claim 1, characterized in that, The oxygen content in the alloy powder described in step 1 is ≤400ppm, and the powder particle size is ≤100um.

4. The preparation method according to claim 1, characterized in that, The vacuum degree of the degassing and sealing operation in step 1 is ≤2*E-3Pa.

5. The preparation method according to claim 1, characterized in that, The hot isostatic pressing (HIP) sintering operation is as follows: the temperature is increased from room temperature to 605℃ at a heating rate of 10℃ / min, and the pressure is naturally increased to 50MPa during the heating process, and the temperature and pressure are maintained for 60min; then the temperature is increased to 900℃~950℃ at a heating rate of 5℃ / min, and the pressure is increased to ≥110MPa when the temperature is reached, and then the temperature and pressure are maintained for 210min~240min, and after the end, the pressure and temperature are naturally reduced with the furnace.

6. A NiFeWAl alloy target material, prepared by any one of the preparation methods described in claims 1 to 5.

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