Method for preparing NiFeWAl alloy target material through hot 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 through a hot pressing method, and NiFeWAl alloy powder is subjected to hot pressing sintering to prepare the NiFeWAl alloy target material. The molar percentage of Ni atoms in the NiFeWAl alloy powder is 65%-75%; the molar percentage of Fe atoms is 20%-30%; according to the technological parameters of hot pressing sintering, the temperature of the NiFeWAl alloy powder is increased to 1100-1200 DEG C through a gradient temperature increasing method, heat preservation is conducted, then the pressure is increased to 30-40 MPa, and heat preservation and pressure maintaining continue to be conducted for 90-120 min. By using the alloy powder, the original impurity problem is reduced, then the temperature and pressure of each gradient in the hot pressing sintering process are precisely controlled, the problems of uneven component distribution and poor deformability caused by conventional smelting and plastic deformation due to large melting point difference of all components of the alloy are solved, grains are refined, and the product quality is improved. And therefore, the NiFeWAl alloy target material with high performance is prepared. Meanwhile, the invention 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 pressing method and the NiFeWAl alloy target material. Background Art

[0002] Magnetron sputtering is one of the main technologies for preparing thin films. It has the advantages of high film purity, good density, strong bonding force, etc., and is used in various fields. The performance of the film is determined by the sputtering target material. The corresponding target material can be selected according to the purpose of different films. With the development of thin film technology, the existing target materials can no longer meet people's needs.

[0003] NiFeWAl alloy target is a target material used in the field of magnetic storage. It belongs to Ni-Fe based alloy material, to which W and Al elements are added to improve its performance, but it also increases the difficulty of manufacturing accordingly. The NiFeWAl alloy target material prepared by the previous smelting and forging method has problems such as component segregation and low magnetic permeability. Therefore, it is urgent to prepare high-performance NiFeWAl alloy target material.

[0004] 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

[0005] The object of the present invention is to provide a method for preparing a NiFeWAl alloy target by hot pressing. The alloy powder is prepared in advance, and then the temperature and pressure changes during hot pressing and sintering are accurately controlled to solve the problems of uneven component distribution and poor deformation ability caused by conventional smelting and plastic deformation due to the large difference in melting points of the alloy components, thereby preparing a high-performance NiFeWAl alloy target.

[0006] At the same time, the invention also discloses a NiFeWAl alloy target material.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

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

[0009] The process parameters of the hot pressing sintering are: heating the NiFeWAl alloy powder to 1150° C. to 1200° C. by a gradient heating method and keeping the temperature, then pressurizing to 30 MPa to 40 MPa, and continuing to keep the temperature and pressure for 90 min to 120 min.

[0010] In the present invention, the raw material used is NiFeWAl alloy powder, which has a lower oxygen content than that of directly using a single substance powder, and the prepared NiFeWAl alloy target can have a higher magnetic permeability; in addition, the addition of Al element can optimize the magnetic anisotropy of the alloy target, which is helpful to improve the magnetic recording efficiency, and the W element can improve the hardness and wear resistance of the alloy target; for this alloy with special components, a specific gradient temperature rise hot pressing sintering process is adopted, and Al is first pre-alloyed to avoid its melting and cause component segregation, and the temperature of each gradient is accurately controlled to make the component distribution uniform, refine the alloy grains, and reduce the obstruction to the magnetic field, thereby obtaining a finished alloy target with high magnetic permeability.

[0011] Preferably, the molar percentage of the Ni atoms is 68% to 75%, and the molar percentage of the 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 ≤75um;

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

[0016] Preferably, the gradient heating method is operated as follows: heating from room temperature to 590°C-610°C at a heating rate of 10°C / min, and keeping warm for 20min-40min; then continuing to heat to 930°C-970°C, and keeping warm for 40min-80min; then heating to 1100°C-1200°C at a heating rate of 5°C / min, and keeping warm for 40min-80min. After that, pressurizing to 30MPa-40MPa within 60min, and continuing to keep warm and pressure for 90min-120min. After that, the pressure and temperature are naturally reduced with the furnace.

[0017] More preferably, the gradient temperature rise method is operated as follows: heating from room temperature to 600°C at a heating rate of 10°C / min, and keeping warm for 30 minutes; then continuing to heat to 950°C and keeping warm for 60 minutes; then heating to 1150°C~1200°C at a heating rate of 5°C / min, keeping warm for 60 minutes, and then pressurizing to 35MPa within 60 minutes after completion, and continuing to keep warm and pressure for 105min~120min, and then naturally reducing pressure and cooling with the furnace after completion.

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

[0019] The beneficial effects of the present invention are:

[0020] The present invention reduces the original impurity problem by using alloy powder, and then accurately controls the temperature and pressure of each gradient in the hot pressing sintering process, solves the problems of uneven component distribution and poor deformation ability caused by conventional smelting and plastic deformation due to the large difference in melting points of the alloy components, and refines the grains, thereby preparing a high-performance NiFeWAl alloy target. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flow chart of the process of the present invention. DETAILED DESCRIPTION

[0022] 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.

[0023] Example 1

[0024] Step 1: NiFeWAl alloy with a molar percentage content of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into NiFeWAl alloy powder by vacuum atomization method (VGA), the powder particle size is 75um, and the oxygen content in the powder is ≤400ppm; the powder is loaded into a CC graphite mold, and W foil is placed between the powder and the mold for isolation. After the powder is flattened, it is placed in a pressure head, and then placed in a vacuum hot pressing equipment, and evacuated to a vacuum degree of ≤100Pa;

[0025] 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 200 mesh to obtain NiFeWAl alloy powder.

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

[0027] The temperature was raised from room temperature to 600°C at a heating rate of 10°C / min and kept at that temperature for 30 minutes; then the temperature was continued to be raised to 950°C and kept at that temperature for 60 minutes; then the temperature was raised to 1150°C at a heating rate of 5°C / min and kept at that temperature for 60 minutes. After the temperature was raised, the pressure was increased to 35MPa within 60 minutes and the temperature was kept at that temperature for 105 minutes. After the temperature was lowered naturally with the furnace, the blank target was obtained after the mold was removed.

[0028] 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.

[0029] The above process flow reference Figure 1 .

[0030] Example 2

[0031] Step 1: NiFeWAl alloy with a molar percentage content 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 75um, and the oxygen content in the powder is ≤400ppm; the powder is loaded into a CC graphite mold, and W foil is placed between the powder and the mold for isolation. After the powder is flattened, it is placed in a pressure head, and then placed in a vacuum hot pressing equipment, and evacuated to a vacuum degree of ≤100Pa;

[0032] 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 200 mesh to obtain NiFeWAl alloy powder.

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

[0034] The temperature was raised from room temperature to 600°C at a heating rate of 10°C / min and kept at that temperature for 30 minutes; then the temperature was continued to be raised to 950°C and kept at that temperature for 60 minutes; then the temperature was raised to 1150°C at a heating rate of 5°C / min and kept at that temperature for 60 minutes. After the temperature was raised, the pressure was increased to 35MPa within 60 minutes and the temperature was kept at that temperature for 105 minutes. After the temperature was lowered naturally with the furnace, the blank target was obtained after the mold was removed.

[0035] 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.

[0036] Example 3

[0037] Step 1: NiFeWAl alloy with a molar percentage content 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 75um, and the oxygen content in the powder is ≤400ppm; the powder is loaded into a CC graphite mold, and W foil is placed between the powder and the mold for isolation. After the powder is flattened, it is placed in a pressure head, and then placed in a vacuum hot pressing equipment, and evacuated to a vacuum degree of ≤100Pa;

[0038] 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 200 mesh to obtain NiFeWAl alloy powder.

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

[0040] The temperature was raised from room temperature to 600°C at a heating rate of 10°C / min and kept at that temperature for 30 minutes; then the temperature was continued to be raised to 950°C and kept at that temperature for 60 minutes; then the temperature was raised to 1150°C at a heating rate of 5°C / min and kept at that temperature for 60 minutes. After the temperature was raised, the pressure was increased to 35MPa within 60 minutes and the temperature was kept at that temperature for 105 minutes. After the temperature was lowered naturally with the furnace, the blank target was obtained after the mold was removed.

[0041] 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.

[0042] Example 4

[0043] Step 1: NiFeWAl alloy with a molar percentage content of 68% Ni, 24% Fe, 6% W, and 2% Al is prepared into NiFeWAl alloy powder by vacuum atomization method (VGA), the powder particle size is 75um, and the oxygen content in the powder is ≤400ppm; the powder is loaded into a CC graphite mold, and W foil is placed between the powder and the mold for isolation. After the powder is flattened, it is placed in a pressure head, and then placed in a vacuum hot pressing equipment, and evacuated to a vacuum degree of ≤100Pa;

[0044] 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 200 mesh to obtain NiFeWAl alloy powder.

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

[0046] The temperature was raised from room temperature to 610°C at a heating rate of 10°C / min, and kept at that temperature for 20 minutes; then the temperature was continued to be raised to 970°C, and kept at that temperature for 40 minutes; then the temperature was raised to 1200°C at a heating rate of 5°C / min, and kept at that temperature for 40 minutes. After that, the temperature was pressurized to 40MPa within 60 minutes, and the temperature was kept at that temperature for 90 minutes. After that, the temperature was naturally reduced with the furnace, and the blank target was obtained after the mold was removed.

[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: NiFeWAl alloy with a molar percentage content 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 75um, and the oxygen content in the powder is ≤400ppm; the powder is loaded into a CC graphite mold, and W foil is placed between the powder and the mold for isolation. After the powder is flattened, it is placed in a pressure head, and then placed in a vacuum hot pressing equipment, and evacuated to a vacuum degree of ≤100Pa;

[0050] 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 200 mesh to obtain NiFeWAl alloy powder.

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

[0052] The temperature was raised from room temperature to 590°C at a heating rate of 10°C / min and kept at that temperature for 20 minutes; then the temperature was continued to be raised to 930°C and kept at that temperature for 80 minutes; then the temperature was raised to 1100°C at a heating rate of 5°C / min and kept at that temperature for 80 minutes. After that, the temperature was pressurized to 30MPa within 60 minutes and kept at that temperature for 120 minutes. After that, the temperature was naturally reduced with the furnace and the blank target was obtained after the mold was removed.

[0053] 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.

[0054] Example 6

[0055] The specific experimental steps are generally the same as those in Example 1, except that in step 2, the specific process of the gradient heating method is as follows: heating from room temperature to 600°C at a heating rate of 10°C / min, and keeping warm for 30 minutes; then heating to 1150°C at a heating rate of 5°C / min, keeping warm for 60 minutes, and then pressurizing to 35MPa within 60 minutes, and continuing to keep warm and pressure for 120 minutes. After completion, the pressure and temperature are naturally reduced with the furnace.

[0056] Example 7

[0057] The specific experimental steps are generally the same as those in Example 1, except that in step 2, the specific process of the gradient heating method is: heating from room temperature to 950°C at a heating rate of 10°C / min, and keeping warm for 60 minutes; then heating to 1150°C at a heating rate of 5°C / min, keeping warm for 60 minutes, and then pressurizing to 35MPa within 60 minutes after the end, and continuing to keep warm and pressurized for 120 minutes. After the end, the pressure and temperature are naturally reduced with the furnace.

[0058] Comparative Example 1

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

[0060] Comparative Example 2

[0061] The specific experimental steps are generally the same as those in Example 1, except that in step 2, the specific process of the gradient temperature increase method is:

[0062] The temperature was raised from room temperature to 600°C at a heating rate of 10°C / min and kept at that temperature for 30 minutes; then the temperature was continued to be raised to 950°C and kept at that temperature for 60 minutes; then the temperature was raised to 1050°C at a heating rate of 5°C / min and kept at that temperature for 60 minutes. After that, the temperature was pressurized to 35MPa within 60 minutes and kept at that temperature for 105 minutes. After that, the temperature was naturally reduced with the furnace and the blank target was obtained after the mold was removed.

[0063] Comparative Example 3

[0064] The specific experimental steps are generally the same as those in Example 1, except that in step 2, the specific process of the gradient temperature increase method is:

[0065] The temperature was raised from room temperature to 600°C at a heating rate of 10°C / min and kept at that temperature for 30 minutes; then the temperature was continued to be raised to 950°C and kept at that temperature for 60 minutes; then the temperature was raised to 1250°C at a heating rate of 5°C / min and kept at that temperature for 60 minutes. After the temperature was raised, the temperature was pressurized to 35MPa within 60 minutes and kept at that temperature for 105 minutes. After the temperature was lowered naturally with the furnace, the blank target was obtained after the sheath was removed.

[0066] Performance Testing

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

[0068] The density of the target material was measured using the Archimedes drainage method;

[0069] The metallographic microscope was used for observation, and the intercept method was used to calculate the average grain size;

[0070] Test the magnetic permeability (PTF) 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 Alloy target material performance data

[0074]

[0075] Conclusion Analysis

[0076] It can be seen from the data of Examples 1 to 7 that 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 more than 99.2%, an average grain size of about 40 um, and a uniform color in appearance. Among them, the most important magnetic permeability index is more than 25%, and Example 1 is 29%.

[0077] Comparing the data of Comparative Example 1 and Example 1, it can be seen that after Ni powder, Fe powder, W powder and Al powder are used as raw materials instead of alloy powder in Comparative Example 1, the magnetic permeability of the finished NiFeWAl alloy target obtained is only 8%, which is 21% lower than that of the example. This is because Ni powder, Fe powder, W powder and Al powder contain relatively high oxygen impurities, which cannot be eliminated in the subsequent sintering process, resulting in low magnetic permeability. It can be seen that the use of alloy powder preparation can improve the magnetic permeability of the finished product.

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

[0079] In Comparative Example 3, based on Example 1, the sintering temperature in step 2 is increased to 1250°C. The high temperature causes excessive grain growth of the alloy, and the average grain size reaches 80um. Oversized grains will hinder the transmission of the magnetic field, causing the magnetic permeability of the finished target material to drop to 10%.

[0080] 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 pressing, characterized in that: The NiFeWAl alloy powder is prepared by hot pressing and sintering; the molar percentage of Ni atoms in the NiFeWAl alloy powder is 65% to 75%; the molar percentage of Fe atoms is 20% to 30%; The process parameters of the hot pressing sintering are: heating the NiFeWAl alloy powder to 1100° C. to 1200° C. by a gradient heating method and keeping the temperature, then pressurizing the powder to 30 MPa to 40 MPa, and keeping the temperature and pressure for 90 min to 120 min.

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 in the alloy powder is ≤500ppm, and the powder particle size is ≤75um.

6. The preparation method according to claim 1, characterized in that: Before hot pressing and sintering, a vacuum operation was performed, and the vacuum degree was ≤100Pa.

7. The preparation method according to claim 1, characterized in that: The gradient heating method is operated as follows: heating from room temperature to 590°C-610°C at a heating rate of 10°C / min, and keeping the temperature for 20min-40min; then continuing to heat to 930°C-970°C, and keeping the temperature for 40min-80min; then heating to 1100°C-1200°C at a heating rate of 5°C / min, and keeping the temperature for 40minn-80min. After the heating is completed, the pressure is increased to 30MPa-40MPa within 60min, and the temperature is kept for 90min-120min. After the heating is completed, the pressure and temperature are naturally reduced along with the furnace.

8. The preparation method according to claim 7, characterized in that: The gradient heating method is operated as follows: heating from room temperature to 600°C at a heating rate of 10°C / min, and keeping warm for 30 minutes; then continuing to heat to 950°C and keeping warm for 60 minutes; then heating to 1150°C~1200°C at a heating rate of 5°C / min, keeping warm for 60 minutes, and after that pressurizing to 35MPa within 60 minutes, and continuing to keep warm and pressure for 105min~120min, and after that, naturally reducing pressure and temperature 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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