A method for preparing a ni-fe-w-al alloy target material by a hot-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-pressing method, wherein the NiFeWAl alloy powder is prepared by hot-pressing sintering; the mole percentage of Ni atoms in the NiFeWAl alloy powder is 65% to 75%; the mole percentage of Fe atoms is 20% to 30%; and the process parameters of the hot-pressing sintering are as follows: the NiFeWAl alloy powder is heated to 1100 DEG C to 1200 DEG C by using a gradient heating method and then is kept warm, and then is pressurized to 30MPa to 40MPa and kept warm and pressurized for 90min to 120min. By using the alloy powder, the problem of impurities brought by the original process is reduced, and then the temperature and pressure of each gradient in the hot-pressing sintering process are accurately controlled, so that the problems of uneven component distribution and poor deformation ability caused by the large difference between the melting points of the components of the alloy and brought by the conventional melting and plastic deformation are solved, and the grains are refined, so that the high-performance NiFeWAl alloy target material is prepared. Meanwhile, the application discloses a NiFeWAl alloy target material.

Description

TECHNICAL FIELD

[0001] 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 pressing method and the NiFeWAl alloy target material. BACKGROUND

[0002] Magnetron sputtering is one of the main technologies for preparing thin films, and has the advantages of high film purity, good compactness, strong bonding force and the like, and is applied in various fields. The performance of the thin film is determined by the sputtering target material, and corresponding target materials can be selected according to the purposes of different thin films. With the development of thin film technology, the existing types of target materials cannot meet the needs of people.

[0003] The NiFeWAl alloy target material is a target material applied in the field of magnetic storage and belongs to a Ni-Fe-based alloy material, wherein W and Al elements are added, the purpose is to improve the performance, but the manufacturing difficulty is also increased accordingly. The NiFeWAl alloy target material prepared by the previous smelting and forging method has problems of composition segregation and low magnetic permeability, and therefore, it is urgent to prepare a high-performance NiFeWAl alloy target material.

[0004] Therefore, the technical problem to be solved by the application is how to prepare a high-performance NiFeWAl alloy target material. SUMMARY

[0005] The application aims to provide a method for preparing a NiFeWAl alloy target material by a hot pressing method. The alloy powder is prepared in advance, and the temperature and pressure changes in the hot pressing sintering process are accurately controlled. The problems of uneven composition distribution and poor deformation ability caused by the large difference in melting points of the components of the alloy in the conventional smelting and plastic deformation are solved, so that a high-performance NiFeWAl alloy target material is prepared.

[0006] Meanwhile, the application also discloses a NiFeWAl alloy target material.

[0007] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0008] A method for preparing a NiFeWAl alloy target material by a hot pressing method, wherein the NiFeWAl alloy powder is prepared by hot pressing sintering. The molar percentage of Ni atoms in the NiFeWAl alloy powder is 65% to 75%, and the molar percentage of Fe atoms is 20% to 30%.

[0009] The process parameters of the hot pressing sintering are as follows: the NiFeWAl alloy powder is heated to 1150 DEG C to 1200 DEG C by using a gradient heating method and is then kept warm, and then the pressure is increased to 30 MPa to 40 MPa, and the keeping warm and pressure maintaining is continued for 90 min to 120 min.

[0010] In this invention, the raw material used is NiFeWAl alloy powder, which has a lower oxygen content than using elemental powder directly, resulting in a NiFeWAl alloy target with higher magnetic permeability. Furthermore, the addition of Al optimizes the magnetic anisotropy of the alloy target, improving magnetic recording efficiency, while W increases the hardness and wear resistance of the alloy target. For this alloy with its specific composition, a specific gradient heating hot-pressing sintering process is employed. Al is pre-alloyed to prevent melting and compositional segregation. The temperature of each gradient is precisely controlled to ensure uniform composition distribution, refine the alloy grains, and reduce the obstruction to the magnetic field, thereby obtaining a high-permeability alloy target.

[0011] Preferably, the molar percentage of Ni atoms is 68% to 75%, and the molar percentage of Fe atoms is 24% to 30%.

[0012] Preferably, the molar percentage ratio of Ni, Fe, W and Al in the alloy target is 65-75:20-30:4-6:1-2.

[0013] 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.

[0014] Preferably, the oxygen content in the alloy powder is ≤500ppm, and the powder particle size is ≤75µm;

[0015] Preferably, a vacuuming operation is performed before hot pressing and sintering, with a vacuum degree ≤100Pa.

[0016] Preferably, the gradient heating method is operated as follows: the temperature is increased from room temperature to 590℃~610℃ at a heating rate of 10℃ / min, and held for 20min~40min; then the temperature is increased to 930℃~970℃ and held for 40min~80min; then the temperature is increased to 1100℃~1200℃ at a heating rate of 5℃ / min and held for 40min~80min; after the end, the pressure is increased to 30MPa~40MPa within 60min, and the temperature and pressure are maintained for 90min~120min; after the end, the pressure and temperature are naturally reduced with the furnace.

[0017] More preferably, the gradient heating method is operated as follows: the temperature is increased from room temperature to 600°C at a heating rate of 10°C / min and held for 30 min; then the temperature is increased to 950°C and held for 60 min; then the temperature is increased to 1150°C to 1200°C at a heating rate of 5°C / min and held for 60 min; after the end, the pressure is increased to 35 MPa within 60 min, and the temperature and pressure are held for 105 min to 120 min; after the end, the pressure and temperature are naturally reduced with the furnace.

[0018] In addition, a NiFeWAl alloy target material is disclosed, which is prepared by the method described above.

[0019] The beneficial effects of this invention are:

[0020] This invention reduces the impurity problems caused by using alloy powder, and then precisely controls the temperature and pressure at each gradient during the hot pressing sintering process. This solves the problem of uneven component distribution and poor deformation ability caused by the large difference in melting points of the alloy components, which leads to conventional melting and plastic deformation. Furthermore, it refines the grains, thereby producing a high-performance NiFeWAl alloy target. Attached Figure Description

[0021] Figure 1 This is a flowchart of the process of the present invention. Detailed Implementation

[0022] 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.

[0023] Example 1

[0024] Step 1: Prepare NiFeWAl alloy powder with a molar percentage of 68% Ni, 24% Fe, 6% W, and 2% Al using vacuum atomization (VGA). The powder particle size is 75 μm, and the oxygen content in the powder is ≤400 ppm. Load the powder into a CC graphite mold, with W foil placed between the powder and the mold for isolation. After leveling the powder, place it into a pressure head and then into a vacuum hot press equipment, where a vacuum degree is ≤100 Pa.

[0025] 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 it in a vacuum at 1500℃ in an alumina crucible and hold it for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 200-mesh sieve to obtain NiFeWAl alloy powder.

[0026] Step 2: Sintering is carried out using the gradient heating method. The specific process of the gradient heating method is as follows:

[0027] The temperature is increased from room temperature to 600℃ at a rate of 10℃ / min and held for 30 min; then the temperature is increased to 950℃ and held for 60 min; then the temperature is increased to 1150℃ at a rate of 5℃ / min and held for 60 min. After the temperature is increased, the pressure is increased to 35MPa within 60 min and the temperature and pressure are maintained for 105 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the mold is removed, the blank target billet is obtained.

[0028] 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.

[0029] The above process flow is for reference. Figure 1 .

[0030] Example 2

[0031] Step 1: Prepare NiFeWAl alloy powder with a molar percentage of 75% Ni, 20% Fe, 4% W, and 1% Al using vacuum atomization (VGA). The powder particle size is 75 μm, and the oxygen content in the powder is ≤400 ppm. Load the powder into a CC graphite mold, with W foil placed between the powder and the mold for isolation. After leveling the powder, place it into a pressure head and then into a vacuum hot press equipment, where a vacuum degree is ≤100 Pa.

[0032] 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 it in a vacuum at 1500℃ in an alumina crucible and hold it for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 200-mesh sieve to obtain NiFeWAl alloy powder.

[0033] Step 2: Sintering is carried out using the gradient heating method. The specific process of the gradient heating method is as follows:

[0034] The temperature is increased from room temperature to 600℃ at a rate of 10℃ / min and held for 30 min; then the temperature is increased to 950℃ and held for 60 min; then the temperature is increased to 1150℃ at a rate of 5℃ / min and held for 60 min. After the temperature is increased, the pressure is increased to 35MPa within 60 min and the temperature and pressure are maintained for 105 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the mold is removed, the blank target billet is obtained.

[0035] 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.

[0036] Example 3

[0037] Step 1: Prepare NiFeWAl alloy powder with a molar percentage of 65% Ni, 30% Fe, 4% W, and 1% Al using vacuum atomization (VGA). The powder particle size is 75 μm, and the oxygen content in the powder is ≤400 ppm. Load the powder into a CC graphite mold, with W foil placed between the powder and the mold for isolation. After leveling the powder, place it into a pressure head and then into a vacuum hot press equipment, where a vacuum degree is ≤100 Pa.

[0038] 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 it in a vacuum at 1500℃ in an alumina crucible and hold it for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 200-mesh sieve to obtain NiFeWAl alloy powder.

[0039] Step 2: Sintering is carried out using the gradient heating method. The specific process of the gradient heating method is as follows:

[0040] The temperature is increased from room temperature to 600℃ at a rate of 10℃ / min and held for 30 min; then the temperature is increased to 950℃ and held for 60 min; then the temperature is increased to 1150℃ at a rate of 5℃ / min and held for 60 min. After the temperature is increased, the pressure is increased to 35MPa within 60 min and the temperature and pressure are maintained for 105 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the mold is removed, the blank target billet is obtained.

[0041] 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.

[0042] Example 4

[0043] Step 1: Prepare NiFeWAl alloy powder with a molar percentage of 68% Ni, 24% Fe, 6% W, and 2% Al using vacuum atomization (VGA). The powder particle size is 75 μm, and the oxygen content in the powder is ≤400 ppm. Load the powder into a CC graphite mold, with W foil placed between the powder and the mold for isolation. After leveling the powder, place it into a pressure head and then into a vacuum hot press equipment, where a vacuum degree is ≤100 Pa.

[0044] 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 it in a vacuum at 1500℃ in an alumina crucible and hold it for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 200-mesh sieve to obtain NiFeWAl alloy powder.

[0045] Step 2: Sintering is carried out using the gradient heating method. The specific process of the gradient heating method is as follows:

[0046] The temperature is increased from room temperature to 610℃ at a rate of 10℃ / min and held for 20 min; then the temperature is increased to 970℃ and held for 40 min; then the temperature is increased to 1200℃ at a rate of 5℃ / min and held for 40 min. After the temperature is increased, the pressure is increased to 40MPa within 60 min and the temperature and pressure are maintained for 90 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the mold is removed, the blank target billet is obtained.

[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: Prepare NiFeWAl alloy powder with a molar percentage of 68% Ni, 24% Fe, 6% W, and 2% Al using vacuum atomization (VGA). The powder particle size is 75 μm, and the oxygen content in the powder is ≤400 ppm. Place the powder into a CC graphite mold, with W foil placed between the powder and the mold for isolation. After leveling the powder, place it into a pressure head and then into a vacuum hot press equipment, where a vacuum degree is ≤100 Pa.

[0050] 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 it in a vacuum at 1500℃ in an alumina crucible and hold it for 20min to 30min. Then perform argon atomization with an argon pressure of 3MPa to 4MPa. The resulting powder is sieved through a 200-mesh sieve to obtain NiFeWAl alloy powder.

[0051] Step 2: Sintering is carried out using the gradient heating method. The specific process of the gradient heating method is as follows:

[0052] The temperature is increased from room temperature to 590℃ at a rate of 10℃ / min and held for 20 min; then the temperature is increased to 930℃ and held for 80 min; then the temperature is increased to 1100℃ at a rate of 5℃ / min and held for 80 min. After the temperature is increased, the pressure is increased to 30MPa within 60 min and the temperature and pressure are maintained for 120 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the mold is removed, the blank target billet is obtained.

[0053] 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.

[0054] Example 6

[0055] The specific experimental steps are largely the same as in Example 1. The difference is that in step 2, the specific process of the gradient heating method is as follows: the temperature is increased from room temperature to 600℃ at a heating rate of 10℃ / min and held for 30min; then the temperature is increased to 1150℃ at a heating rate of 5℃ / min and held for 60min. After the end, the pressure is increased to 35MPa within 60min and the temperature and pressure are maintained for another 120min. After the end, the pressure and temperature are naturally reduced with the furnace.

[0056] Example 7

[0057] The specific experimental steps are largely the same as in Example 1. The difference is that in step 2, the specific process of the gradient heating method is as follows: the temperature is increased from room temperature to 950°C at a heating rate of 10°C / min and held for 60 min; then the temperature is increased to 1150°C at a heating rate of 5°C / min and held for 60 min. After the end, the pressure is increased to 35 MPa within 60 min, and the temperature and pressure are maintained for another 120 min. After the end, the pressure and temperature are naturally reduced with the furnace.

[0058] Comparative Example 1

[0059] 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 75 μm, the average particle size of Fe powder being 75 μm, the average particle size of W powder being 45 μm, and the average particle size of Al powder being 45 μm.

[0060] Comparative Example 2

[0061] The specific experimental steps are largely the same as in Example 1, except that in step 2, the specific process of the gradient heating method is as follows:

[0062] The temperature is increased from room temperature to 600℃ at a rate of 10℃ / min and held for 30 min; then the temperature is increased to 950℃ and held for 60 min; then the temperature is increased to 1050℃ at a rate of 5℃ / min and held for 60 min. After the temperature is increased, the pressure is increased to 35MPa within 60 min and the temperature and pressure are maintained for 105 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the mold is removed, the blank target billet is obtained.

[0063] Comparative Example 3

[0064] The specific experimental steps are largely the same as in Example 1, except that in step 2, the specific process of the gradient heating method is as follows:

[0065] The temperature is increased from room temperature to 600℃ at a rate of 10℃ / min and held for 30 min; then the temperature is increased to 950℃ and held for 60 min; then the temperature is increased to 1250℃ at a rate of 5℃ / min and held for 60 min. After the temperature is increased, the pressure is increased to 35MPa within 60 min and the temperature and pressure are maintained for 105 min. After the temperature is increased, the pressure and temperature are naturally reduced in the furnace. After the cladding is removed, the blank target billet is obtained.

[0066] Performance testing

[0067] The samples prepared in each embodiment and comparative example were tested for the following items: purity, density, average grain size, magnetic permeability, and appearance.

[0068] The density of the target material was measured using the Archimedes displacement method.

[0069] The average grain size was calculated using the intercept method after observation with a metallographic microscope.

[0070] The permeability (PTF) was tested according to ASTM F2086-01 standard.

[0071] Purity was tested using GDMS.

[0072] The specific test results are shown in Table 1;

[0073] Table 1 Performance Data of Alloy Targets

[0074]

[0075] Conclusion Analysis

[0076] As can be seen from the data in Examples 1 to 7, the NiFeWAl alloy targets with different component contents prepared by the technical solution of the present invention have a purity of ≥99.95%, a density of over 99.2%, an average grain size that can be controlled at around 40 μm, and a uniform appearance. Among them, the most important magnetic permeability index is above 25%, with Example 1 having 29%.

[0077] Comparing the data of Comparative Example 1 and Example 1, it can be seen that after replacing alloy powder with Ni powder, Fe powder, W powder, and Al powder as raw materials, the magnetic permeability of the finished NiFeWAl alloy target material obtained in Comparative Example 1 is only 8%, which is 21% lower than that in Example 1. This is because Ni powder, Fe powder, W powder, and Al powder contain high levels of oxygen impurities, which cannot be eliminated during the subsequent sintering process, resulting in a lower magnetic permeability. This shows that using alloy powder can improve the magnetic permeability of the finished product.

[0078] Comparative Example 2, based on Example 1, reduced the sintering temperature in step 2 to 1050°C. The insufficient temperature resulted in a low degree of alloy powder fusion, which led to a decrease in the density of the final product and a poor magnetic permeability of 15%.

[0079] Comparative Example 3, based on Example 1, increased the sintering temperature in step 2 to 1250°C. The excessively high temperature caused excessive grain growth in the alloy, with an average grain size of 80 μm. The excessively large grain size would hinder the transmission of the magnetic field, resulting in a decrease in the permeability of the finished target material to 10%.

[0080] 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 pressing, characterized in that, NiFeWAl alloy powder was prepared by hot pressing and sintering. The hot pressing sintering process parameters are as follows: NiFeWAl alloy powder is heated to 1100℃~1200℃ using a gradient heating method and held at that temperature, then pressurized to 30MPa~40MPa, and held at that temperature and pressure for 90min~120min. The molar percentage ratio of Ni, Fe, W and Al in the alloy target is 65~75:20~30:4~6:1~2; The gradient heating method is operated as follows: the temperature is increased from room temperature to 590℃~610℃ at a heating rate of 10℃ / min, and held for 20min~40min; then the temperature is increased to 930℃~970℃ and held for 40min~80min; then the temperature is increased to 1100℃~1200℃ at a heating rate of 5℃ / min and held for 40min~80min. After the temperature is increased, the pressure is increased to 30MPa~40MPa within 60min, and the temperature and pressure are maintained for 90min~120min. After the temperature is increased, the pressure and temperature are naturally reduced with the furnace.

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 alloy powder has an oxygen content of ≤500ppm and a particle size of ≤75µm.

4. The preparation method according to claim 1, characterized in that, A vacuuming operation was performed before hot pressing and sintering, with a vacuum degree of ≤100Pa.

5. The preparation method according to claim 1, characterized in that, The gradient heating method is operated as follows: the temperature is increased from room temperature to 600℃ at a heating rate of 10℃ / min and held for 30min; then the temperature is increased to 950℃ and held for 60min; then the temperature is increased to 1150℃~1200℃ at a heating rate of 5℃ / min and held for 60min. After the temperature is increased, the pressure is increased to 35MPa within 60min and the temperature and pressure are maintained for 105min~120min. After the temperature is increased, 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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