Method for preparing NiFeWAl alloy target material through hot isostatic pressing method and NiFeWAl alloy target material

Abstract

The invention 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, which specifically comprises the following steps: step 1, preparing NiFeWAl alloy into NiFeWAl alloy powder by adopting a vacuum atomization method, filling the powder into a sheath, welding the sheath after the powder is flattened, and then carrying out degassing and gas closing operation; 2, performing hot isostatic pressing sintering operation on the sheath obtained in the step 1, and removing the sheath after sintering to obtain a blank target blank; 3, the blank target blank is machined, and a finished product NiFeWAl alloy target material is obtained; the NiFeWAl alloy target material contains Ni atoms, Fe atoms, W atoms and Al atoms, the atomic percent of the Ni atoms is 65%-75%, and the atomic percent of the Fe atoms is 20%-30%. Meanwhile, the invention further discloses the NiFeWAl alloy target material.

Description

Technical Field

[0001] The invention 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 the NiFeWAl alloy target material. Background Art

[0002] Magnetron sputtering is a technology widely used in the fields of semiconductor integrated circuits, solar photovoltaics, etc. It uses ions generated by an ion source to form an ion beam after acceleration and aggregation in a vacuum, bombarding the solid surface. The ions and the atoms on the solid surface exchange kinetic energy, and finally make the atoms on the solid surface leave the solid and deposit on the substrate surface to form a thin film. Among them, the bombarded solid is called a sputtering target, which is one of the most important basic materials.

[0003] With the development of magnetic recording film technology, the required sputtering target materials are also constantly changing. In the prior art, there are generally two conventional methods for preparing target materials. One is to prepare them by forging, rolling and heat treatment after smelting 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 is to prepare them by powder metallurgy. This method is suitable for difficult-to-deform metals or high-temperature alloys.

[0004] NiFeWAl alloy target is a new type of target material developed by our company. It is used in the field of magnetic storage. W and Al elements are added to it. The addition of W makes the hardness of the alloy higher and the plastic deformation ability lower. At the same time, Al has a low melting point and a small content, which easily leads 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 target. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a NiFeWAl alloy target by hot isostatic pressing, and to solve the problem of uneven component distribution caused by the large difference in melting points of the alloy components by accurately controlling the changes in temperature and pressure during the hot isostatic pressing sintering process, thereby preparing a high-performance NiFeWAl alloy target.

[0007] At the same time, the invention also discloses a NiFeWAl alloy target material.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing a NiFeWAl alloy target by hot isostatic pressing, specifically comprising the following steps:

[0010] Step 1: NiFeWAl alloy is prepared into NiFeWAl alloy powder by vacuum atomization method (VGA), the powder is put into a package, the package is welded after the powder is leveled, and then a degassing and air-sealing operation is performed;

[0011] Step 2: hot isostatic pressing the sleeve obtained in step 1, and removing the sleeve after sintering to obtain a blank target;

[0012] Step 3: machining the blank target to obtain a finished NiFeWAl alloy target;

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

[0014] The NiFeWAl alloy powder used in the present invention, the addition of Al element can optimize the magnetic anisotropy of the alloy target material, which is helpful to enhance the magnetic recording efficiency, and the W element can improve the hardness and wear resistance of the alloy target material. However, the melting point of Al element is relatively low, which is about 660°C, while the melting point of W element is as high as about 3400°C. The melting points of the two are very different. If sintering is performed directly at high temperature, Al will be dissolved first, which is very likely to cause component segregation, resulting in a significant reduction in the performance of the finished alloy target material. In the research of the present invention, it is found that the alloy powder is first sintered at about 600°C, which can make the alloy powder pre-alloyed, thereby improving the melting point of Al. In the subsequent high-temperature sintering, the component distribution can still be kept uniform, so that the finished alloy target material has high wear resistance and maintains excellent magnetic anisotropy.

[0015] Preferably, the molar percentage of the Ni atoms is 68% to 75%, and the molar percentage of the 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 of the alloy powder in step 1 is ≤400ppm, and the powder particle size is ≤100um;

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

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

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

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

[0023] The beneficial effects of the present invention are:

[0024] Ni blocks, Fe blocks, W, and NiAl blocks are used for vacuum melting and pre-alloying to eliminate part of the magnetism of Ni and Fe, and then the alloy powder is prepared by gas atomization to reduce the oxygen content of the powder; the alloy powder is first pre-sintered by hot isostatic pressing to pre-alloy the alloy powder, thereby increasing the melting point of Al. In the subsequent high-temperature sintering, the composition distribution can still be kept uniform, so that the finished alloy target material has high wear resistance and excellent magnetic anisotropy. Finally, a NiFeWAl alloy target material with precise composition control, uniform composition distribution, no segregation, no inclusions, fine and uniform grains, high purity, high density, high magnetic permeability and uniformity in all places is prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Flow chart of the process of the present invention. DETAILED DESCRIPTION

[0026] Below in conjunction with the embodiment of the present invention, technical solution of the present invention will be clearly and completely described, it is obvious that the described embodiment is only a part of the present invention, rather than all embodiments. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. It should be noted that, in the embodiment, those who do not indicate specific conditions, are carried out according to the conditions recommended by normal conditions or manufacturers. Reagents used or instruments that do not indicate manufacturers are conventional products that can be obtained by commercial purchase.

[0027] Example 1

[0028] Step 1: A NiFeWAl alloy having a molar percentage content of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into a NiFeWAl alloy powder by vacuum atomization (VGA), wherein the powder particle size is 100um and the oxygen content in the powder is ≤400ppm; the powder is put into a package, and the package is welded after the powder is leveled, and then the package is placed in a degassing furnace for heating, and a molecular pump is used for degassing, and the vacuum degree is closed after reaching 2*E-3Pa, so that the inside of the package is kept in a vacuum state;

[0029] The specific operation of the vacuum atomization method is: select NiAl alloy (50:50) that can be directly purchased on the market, and then put NiAl alloy blocks, Ni blocks, Fe blocks, and W blocks prepared according to the target ratio into the VGA equipment together, and smelt them at 1500°C in a vacuum alumina crucible, keep warm for 20min~30min, and then perform argon atomization with an argon pressure of 3MPa~4MPa. The obtained powder is sieved with 150 mesh to obtain NiFeWAl alloy powder.

[0030] Step 2: Place the degassed package into a hot isostatic pressing furnace, power on and heat it from room temperature to 605°C at a heating rate of 10°C / min. During the heating process, the pressure is naturally increased to 50MPa, and the temperature is kept at this temperature for 60 minutes. Then, the temperature is increased to 900°C at a heating rate of 5°C / min. When the temperature is reached, the pressure is increased to ≥110MPa, and then the temperature is kept at this temperature for 210 minutes. After the temperature is reached, the pressure is naturally reduced and the temperature is lowered. After sintering, the package is removed to obtain a blank target blank:

[0031] Step 3: Machining the target blank, using a CNC grinder to process the thickness, and a CNC lathe to process the side, and then cleaning, drying and packaging to obtain a finished NiFeWAl alloy target.

[0032] The above process flow reference Figure 1

[0033] Example 2

[0034] Step 1: A NiFeWAl alloy having a molar percentage content of 75% Ni, 20% Fe, 4% W, and 1% Al is prepared into a NiFeWAl alloy powder by vacuum atomization (VGA), wherein the powder particle size is 100um and the oxygen content in the powder is ≤400ppm; the powder is put into a package, and the package is welded after the powder is leveled, and then the package is placed in a degassing furnace for heating, and a molecular pump is used for degassing, and the vacuum degree is closed after reaching 2*E-3Pa, so that the inside of the package is kept in a vacuum state;

[0035] The specific operation of the vacuum atomization method is: select NiAl alloy (50:50) that can be directly purchased on the market, and then put NiAl alloy blocks, Ni blocks, Fe blocks, and W blocks prepared according to the target ratio into the VGA equipment together, and smelt them at 1500°C in a vacuum alumina crucible, keep warm for 20min~30min, and then perform argon atomization with an argon pressure of 3MPa~4MPa. The obtained powder is sieved with 150 mesh to obtain NiFeWAl alloy powder.

[0036] Step 2: Place the degassed package into a hot isostatic pressing furnace, power on and heat it from room temperature to 605°C at a heating rate of 10°C / min. During the heating process, the pressure is naturally increased to 50MPa, and the temperature is kept at this temperature for 60 minutes. Then, the temperature is increased to 900°C at a heating rate of 5°C / min. When the temperature is reached, the pressure is increased to ≥110MPa, and then the temperature is kept at this temperature for 210 minutes. After the temperature is reached, the pressure is naturally reduced and the temperature is lowered. After sintering, the package is removed to obtain a blank target blank:

[0037] Step 3: Machining the target blank, using a CNC grinder to process the thickness, and a CNC lathe to process the side, and then cleaning, drying and packaging to obtain a finished NiFeWAl alloy target.

[0038] Example 3

[0039] Step 1: A NiFeWAl alloy having a molar percentage content of 65% Ni, 30% Fe, 4% W, and 1% Al is prepared into a NiFeWAl alloy powder by vacuum atomization (VGA), wherein the powder particle size is 100um and the oxygen content in the powder is ≤400ppm; the powder is put into a package, and the package is welded after the powder is leveled, and then the package is placed in a degassing furnace for heating, and a molecular pump is used for degassing, and the vacuum degree is closed after reaching 2*E-3Pa, so that the inside of the package is kept in a vacuum state;

[0040] The specific operation of the vacuum atomization method is: select NiAl alloy (50:50) that can be directly purchased on the market, and then put NiAl alloy blocks, Ni blocks, Fe blocks, and W blocks prepared according to the target ratio into the VGA equipment together, and smelt them at 1500°C in a vacuum alumina crucible, keep warm for 20min~30min, and then perform argon atomization with an argon pressure of 3MPa~4MPa. The obtained powder is sieved with 150 mesh to obtain NiFeWAl alloy powder.

[0041] Step 2: Place the degassed package into a hot isostatic pressing furnace, power on and heat it from room temperature to 605°C at a heating rate of 10°C / min. During the heating process, the pressure is naturally increased to 50MPa, and the temperature is kept at this temperature for 60 minutes. Then, the temperature is increased to 900°C at a heating rate of 5°C / min. When the temperature is reached, the pressure is increased to ≥110MPa, and then the temperature is kept at this temperature for 210 minutes. After the temperature is reached, the pressure is naturally reduced and the temperature is lowered. After sintering, the package is removed to obtain a blank target blank:

[0042] Step 3: Machining the target blank, using a CNC grinder to process the thickness, and a CNC lathe to process the side, and then cleaning, drying and packaging to obtain a finished NiFeWAl alloy target.

[0043] Example 4

[0044] Step 1: A NiFeWAl alloy having a molar percentage content of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into a NiFeWAl alloy powder by vacuum atomization (VGA), wherein the powder particle size is 100um and the oxygen content in the powder is ≤400ppm; the powder is put into a package, and the package is welded after the powder is leveled, and then the package is placed in a degassing furnace for heating, and a molecular pump is used for degassing, and the vacuum degree is closed after reaching 2*E-3Pa, so that the inside of the package is kept in a vacuum state;

[0045] The specific operation of the vacuum atomization method is: select NiAl alloy (50:50) that can be directly purchased on the market, and then put NiAl alloy blocks, Ni blocks, Fe blocks, and W blocks prepared according to the target ratio into the VGA equipment together, and smelt them at 1500°C in a vacuum alumina crucible, keep warm for 20min~30min, and then perform argon atomization with an argon pressure of 3MPa~4MPa. The obtained powder is sieved with 150 mesh to obtain NiFeWAl alloy powder.

[0046] Step 2: Place the degassed package into a hot isostatic pressing furnace, power on and heat it from room temperature to 610°C at a heating rate of 10°C / min. During the heating process, the pressure is naturally increased to 55MPa, and the temperature is kept at this temperature for 58 minutes. Then, the temperature is increased to 950°C at a heating rate of 5°C / min. When the temperature is reached, the pressure is increased to ≥110MPa, and then the temperature is kept at this temperature for 180 minutes. After the temperature is reached, the pressure is naturally reduced with the furnace. After sintering, the package is removed to obtain a blank target blank:

[0047] Step 3: Machining the target blank, using a CNC grinder to process the thickness, and a CNC lathe to process the side, and then cleaning, drying and packaging to obtain a finished NiFeWAl alloy target.

[0048] Example 5

[0049] Step 1: A NiFeWAl alloy having a molar percentage content of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into a NiFeWAl alloy powder by vacuum atomization (VGA), wherein the powder particle size is 100um and the oxygen content in the powder is ≤400ppm; the powder is put into a package, and the package is welded after the powder is leveled, and then the package is placed in a degassing furnace for heating, and a molecular pump is used for degassing, and the vacuum degree is closed after reaching 2E-3Pa, so that the inside of the package is kept in a vacuum state;

[0050] The specific operation of the vacuum atomization method is: the specific operation of the vacuum atomization method is: select NiAl alloy (50:50) that can be directly purchased on 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 together, and smelt at 1500°C in alumina crucible under vacuum, keep warm for 20min~30min, and then perform argon atomization with an argon pressure of 3MPa~4MPa. The obtained powder is sieved with 150 mesh to obtain NiFeWAl alloy powder.

[0051] Step 2: Place the degassed package into a hot isostatic pressing furnace, power on and heat it from room temperature to 600°C at a heating rate of 10°C / min. During the heating process, the pressure is naturally increased to 45MPa, and the temperature is kept at this temperature for 62 minutes. Then, the temperature is increased to 850°C at a heating rate of 5°C / min. When the temperature is reached, the pressure is increased to ≥110MPa, and then the temperature is kept at this temperature for 240 minutes. After the temperature is reduced, the pressure and temperature are naturally reduced with the furnace. After sintering, the package is removed to obtain a blank target blank:

[0052] Step 3: Machining the target blank, using a CNC grinder to process the thickness, and a CNC lathe to process the side, and then cleaning, drying and packaging to obtain a finished NiFeWAl alloy target.

[0053] Example 6

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

[0055] Comparative Example 1

[0056] The specific experimental steps are generally the same as those in Example 1, except that, in step 1, Ni powder, Fe powder, W powder and Al powder are directly used instead of the alloy powder according to molar percentage; the particle sizes of Ni powder, Fe powder, W powder and Al powder are all controlled below 100 μm, among which the average particle size of Ni powder is 100 μm, the average particle size of Fe powder is 100 μm, the average particle size of W powder is 45 μm, and the average particle size of Al powder is 45 μm.

[0057] Comparative Example 2:

[0058] The specific experimental steps are generally the same as those in Example 1, except that the specific process of step 2 is as follows: put the degassed package into a hot isostatic pressing furnace, power on and heat it up from room temperature to 605°C at a heating rate of 10°C / min, naturally increase the pressure to 50MPa during the heating process, and keep the temperature for 60min; then heat it up to 800°C at a heating rate of 5°C / min, and when the temperature is reached, pressurize it to ≥110MPa, then keep the temperature for 210min, and then naturally reduce the pressure and temperature with the furnace. After sintering, remove the package to obtain a blank target.

[0059] Comparative Example 3:

[0060] The specific experimental steps are generally the same as those in Example 1, except that the specific process of step 2 is as follows: put the degassed package into a hot isostatic pressing furnace, power on and heat it up from room temperature to 605°C at a heating rate of 10°C / min, naturally increase the pressure to 50MPa during the heating process, and keep the temperature for 60min; then heat it up to 1000°C at a heating rate of 5°C / min, and when the temperature is reached, pressurize it to ≥110MPa, then keep the temperature for 210min, and then naturally reduce the pressure and temperature with the furnace. After sintering, remove the package to obtain a blank target.

[0061] Comparative Example 4:

[0062] The specific experimental steps are generally the same as those in Example 1, except that the specific process of step 2 is as follows: put the degassed package into a hot isostatic pressing furnace, power on and heat it up from room temperature to 605°C at a heating rate of 10°C / min, naturally increase the pressure to 50MPa during the heating process, and keep the temperature for 60min; then heat it up to 800°C at a heating rate of 5°C / min, and when the temperature is reached, pressurize it to 100MPa at the same time, then keep the temperature for 210min, and then naturally reduce the pressure and temperature with the furnace. After sintering, remove the package to obtain a blank target.

[0063] Performance Testing

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

[0065] The density of the target material was measured using the Archimedes drainage method;

[0066] The metallographic microscope was used for observation, and the intercept method was used to calculate the average grain size;

[0067] Test the magnetic permeability (PTF) 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 Alloy target material performance data

[0071]

[0072]

[0073] Conclusion Analysis

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

[0075] From the comparison of the data of Comparative Example 1 and Example 1, it can be seen that after Comparative Example 1 uses Ni powder, Fe powder, W powder and Al powder instead of alloy powder as raw materials, the magnetic permeability of the product NiFeWAl alloy target is very low, only 8%. The main reason is that the oxygen content in Ni powder, Fe powder, W powder and Al powder is relatively high, which cannot be eliminated during the sintering process, resulting in excessively high oxygen content in the final product, thereby causing low magnetic permeability. The use of alloy powder in the present invention can solve this problem.

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

[0077] In Comparative Example 3, based on Example 1, the sintering temperature in Step 2 is increased to 1000°C, which is also beyond the range. The excessively high temperature causes excessive grain growth of the alloy, and the average grain size reaches 80um. Excessively large grains will hinder the transmission of the magnetic field, resulting in a decrease in the magnetic permeability of the finished target material.

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

[0079] It will be apparent to those skilled in the art that the 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 the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a NiFeWAl alloy target by hot isostatic pressing, characterized in that: The specific steps include: Step 1: NiFeWAl alloy is prepared into NiFeWAl alloy powder by vacuum atomization method, the powder is put into a package, the package is welded after the powder is leveled, and then a degassing and air-sealing operation is performed; Step 2: hot isostatic pressing the sleeve obtained in step 1, and removing the sleeve after sintering to obtain a blank target; Step 3: machining the blank target to obtain a finished NiFeWAl alloy target; The NiFeWAl alloy target 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%.

2. The preparation method according to claim 1, characterized in that: The molar percentage of the Ni atoms is 68% to 75%, and the molar percentage of the Fe atoms is 24% to 30%.

3. The preparation method according to claim 1, characterized in that: The molar percentage ratio of Ni, Fe, W and Al in the alloy target material is 65-75:20-30:4-6:1-2.

4. The preparation method according to claim 3, characterized in that: The molar percentage ratio of Ni, Fe, W and Al in the alloy target material is 68-75:24-30:4-6:1-2.

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

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

7. The preparation method according to claim 1, characterized in that: The hot isostatic pressing sintering operation described in step 2 is as follows: heating from room temperature to 600°C~610°C at a heating rate of 10°C / min, naturally increasing the pressure to 45MPa~55MPa during the heating process, and keeping the temperature at that temperature for 58min~62min; then heating to 850°C~950°C at a heating rate of 5°C / min, and when the temperature is reached, the pressure is increased to ≥110MPa, and then the temperature is kept at that temperature for 180min~240min. After the end, the pressure and temperature are naturally reduced with the furnace.

8. The preparation method according to claim 7, characterized in that: The hot isostatic pressing sintering operation is as follows: heating from room temperature to 605°C at a heating rate of 10°C / min, naturally increasing the pressure to 50MPa during the heating process, and maintaining the temperature and pressure for 60min; then heating to 900°C~950°C at a heating rate of 5°C / min, and when the temperature is reached, the pressure is simultaneously increased to ≥110MPa, 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.

9. A NiFeWAl alloy target material, prepared by the preparation method according to any one of claims 1 to 8.

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