Nickel-platinum alloy target material and preparation method thereof

Abstract

The invention belongs to the technical field of nickel-platinum alloy target materials, and discloses a preparation method of a nickel-platinum alloy target material, which specifically comprises the following steps: step 1, magnetic suspension smelting: smelting raw materials nickel and platinum into a NiPt alloy ingot in a magnetic suspension smelting furnace; 2, the NiPt alloy ingot obtained in the step 1 is subjected to vacuum heat treatment operation; 3, the NiPt alloy ingot subjected to vacuum heat treatment is subjected to vacuum hot pressing operation; and 4, the NiPt alloy ingot obtained through hot pressing is cut into a round sheet shape, multi-pass cold rolling treatment is conducted on the NiPt alloy ingot in the round sheet shape, then vacuum recrystallization heat treatment is conducted, and finally the NiPt alloy target material is obtained through machining. Meanwhile, the invention further discloses the nickel-platinum alloy target material.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel-platinum alloy target materials and discloses a nickel-platinum alloy target material and a preparation method thereof. Background Art

[0002] When large-scale integrated circuits enter the 65nm and 45nm nodes, the commonly used titanium silicide and cobalt silicide used in discrete devices such as Schottky diodes and complementary metal oxide semiconductor devices and integrated circuits are no longer applicable. Nickel silicide has the advantages of low sheet resistance, wireless bandwidth efficiency, no bridging phenomenon, low-temperature annealing consumes fewer silicon atoms, and low stress of nickel silicide, making it the first choice for silicides used in 65nm and 45nm technology nodes. However, with the development of market applications, it has been gradually discovered that nickel silicide has poor heat resistance and strong activity, and cannot adapt to high performance and feature sizes below 45nm. The precious metal platinum has good chemical stability, high electrical and thermal conductivity, magnetic properties, and is widely used in the preparation of high-performance thin film materials. The nickel-platinum alloy target can be sputtered into a nickel-platinum thin film through magnetron sputtering technology, and then form NiPtSi silicide with silicon at a certain temperature. It has good heat resistance at the device operating temperature and has metallic conductivity, which can perfectly solve the problems of NiSi.

[0003] However, nickel-platinum targets are highly permeable targets that have a shielding effect on magnetic fields, and sputtering is often difficult to occur. The fundamental solution to this problem is to reduce the magnetic permeability of nickel-platinum targets to reduce the shielding effect and enhance the magnetic field on the target surface. In order to better describe the shielding effect of nickel-platinum targets, it can be quantified by magnetic permeability. Magnetic permeability refers to the ratio of the magnetic field intensity on the surface of the target in the sputtering magnetic field to the magnetic field intensity when there is no target. The higher the magnetic permeability, the higher the magnetic field intensity on the surface of the target, and the easier it is for the target to sputter. Factors that affect the magnetic permeability of nickel-platinum targets mainly include microstructure, thickness, internal stress and other factors. The grain size, grain and composition uniformity, and stress state of the microstructure are usually controlled by forging, hot rolling, cold rolling, and heat treatment methods.

[0004] At present, nickel-platinum alloy targets are mainly prepared by vacuum induction melting followed by hot forging, hot rolling, warm rolling and heat treatment processes. During the melting and hot rolling processes, foreign impurities are easily introduced, thereby reducing the purity of the target. For example, the invention patent CN111304608B obtains a high-grain orientation nickel-platinum target by induction melting and casting, vacuum hot pressing, low-temperature pressing, low-temperature annealing and product processing. Although this invention patent can obtain a high-permeability nickel-platinum target, the melt is easily introduced into the crucible impurities during medium-frequency induction melting, thereby affecting the purity. Another example is the invention patent CN105986138A, which uses ammonium chloroplatinate with a purity greater than or equal to 99.95% and nickel chloride with a purity greater than or equal to 99.99% as raw materials, atomizes and reduces with hydrogen, and then vacuum induction melting and zone melting to obtain ultra-high purity nickel-platinum alloy, and then mechanical rolling and heat treatment to obtain high-purity nickel-platinum target. The preparation process of this patent is cumbersome, which is not conducive to cost control, and the nickel-platinum target is easily oxidized during mechanical rolling, and the oxygen content needs to be further controlled, and the magnetic permeability problem is not involved. In the existing preparation of nickel-platinum targets, the contact between the melt and the crucible during ordinary vacuum induction melting, multiple rolling during hot rolling, and repeated reheating cause severe oxidation, which increases the risk of cracking.

[0005] Therefore, the technical problem that needs to be solved in this case is: how to prepare a NiPt alloy target with high purity and high magnetic permeability. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a NiPt alloy target material, which reduces the introduction of impurities through magnetic levitation melting, solves the stress and other problems caused by magnetic levitation melting through vacuum heat treatment, and finally undergoes vacuum hot pressing to quickly achieve densification and composition homogenization of the material, realize solid solution formation, and finally obtain a high-purity and high-permeability NiPt alloy target material.

[0007] Meanwhile, the invention also discloses a NiPt 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 NiPt alloy target material comprises the following steps:

[0010] Step 1: Magnetic levitation smelting, smelting the raw materials nickel and platinum into NiPt alloy ingots in a magnetic levitation smelting furnace;

[0011] Step 2: performing vacuum heat treatment on the NiPt alloy ingot obtained in step 1;

[0012] Step 3: performing vacuum hot pressing operation on the NiPt alloy ingot after vacuum heat treatment;

[0013] Step 4: The NiPt alloy ingot obtained by hot pressing is cut into disc shapes, the disc-shaped NiPt alloy ingot is subjected to multiple cold rolling processes, and then subjected to vacuum recrystallization heat treatment, and finally machined to obtain a NiPt alloy target.

[0014] In the prior art, the general smelting method will introduce impurities into the NiPt alloy ingot, reducing the purity of the finished product. In the present invention, it is found that the magnetic levitation smelting technology can reduce the contact time between the melt and the crucible, greatly reducing the introduction of impurity content. However, the magnetic levitation smelting time is generally short, and the obtained NiPt alloy ingot will have problems such as thermal stress and uneven composition, resulting in the risk of cracking during subsequent hot pressing and forging. The final product NiPt alloy target has low purity and low magnetic permeability. Therefore, the present invention innovatively performs a vacuum heat treatment operation after magnetic levitation melting, so that the metal material reaches a thermal equilibrium state, and then quickly cools it, so that its organizational structure changes, and the residual stress caused by melting is released through plastic deformation or relaxation process, so that the alloy composition is more uniform; at the same time, liquid argon is used for cooling to prevent the generation of nickel-platinum intermediate phases; vacuum hot pressing is performed after vacuum heat treatment, which can shorten the diffusion distance of nickel and platinum elements, quickly achieve densification and composition homogenization, quickly realize solid solution formation, further prevent the generation of nickel-platinum intermediate phases, and reduce the risk of cracking; and maintaining vacuum throughout the entire process avoids the risk of oxidation and can improve the magnetic permeability of the target material.

[0015] The present invention adopts a new process of magnetic suspension melting, vacuum heat treatment and vacuum hot pressing. Through the cooperation between the functions, the nickel-platinum alloy target material obtained has the characteristics of high purity and high magnetic permeability.

[0016] Preferably, the purity of the raw nickel and raw platinum in step 1 is ≥99.9999%, and the atomic ratio of nickel to platinum is 80-95:5-20.

[0017] Preferably, the magnetic suspension melting temperature is 1500-1650° C., and the melting time is 15-35 min.

[0018] Preferably, the vacuum heat treatment in step 2 is performed at an operating temperature of 950 to 1150° C., for a treatment time of 1 to 4 hours, and is cooled by liquid argon.

[0019] Preferably, the vacuum degree of the vacuum hot pressing operation in step 3 is 10 -3 ~10 -2 Pa, temperature is 1100-1400℃, pressure is 50-100MPa, and vacuum hot pressing time is 2-4h.

[0020] Preferably, the disc-shaped NiPt alloy described in step 4 has a thickness of 3.5 to 6 mm.

[0021] Preferably, the vacuum recrystallization heat treatment temperature in step 4 is 350-550° C. and the time is 1-3 hours.

[0022] In addition, a NiPt alloy target is also disclosed, which is prepared by the above-mentioned preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention adopts magnetic suspension melting technology to reduce the introduction of impurities and greatly improve the purity of the product. The vacuum heat treatment is then used to solve the thermal stress and other problems caused by magnetic suspension melting. After vacuum hot pressing, the material can be quickly densified and the composition can be homogenized to achieve solid solution formation. Finally, after subsequent processing, a high-purity and high-permeability NiPt alloy target is prepared. DETAILED DESCRIPTION

[0025] 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.

[0026] Embodiment 1:

[0027] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 90:10, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1575°C for 25 minutes.

[0028] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 1050° C. with the furnace, and the temperature is kept for 2 hours. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0029] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -3 After the temperature and pressure are raised to 1250°C, the pressure is 75MPa, and the temperature and pressure are maintained for 3h before hot pressing into a cylindrical shape;

[0030] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 5 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 450°C with the furnace, keep it warm for 2 hours, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy, and finally obtain a high-purity and high-permeability NiPt alloy target.

[0031] Example 2

[0032] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 95:5, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1650°C for 35 minutes.

[0033] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 1050° C. with the furnace, and the temperature is kept for 2 hours. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0034] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -3 After the temperature and pressure are raised to 1250°C, the pressure is 75MPa, and the temperature and pressure are maintained for 3h before hot pressing into a cylindrical shape;

[0035] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 5 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 450°C with the furnace, keep it warm for 2 hours, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy, and finally obtain a high-purity and high-permeability NiPt alloy target.

[0036] Example 3

[0037] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 80:20, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1500°C for 15 minutes.

[0038] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 1050° C. with the furnace, and the temperature is kept for 2 hours. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0039] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -3 Pa, then the temperature and pressure are raised to 1250℃, at which time the pressure is 75MPa, and the temperature and pressure are maintained for 3h before hot pressing into a cylindrical shape;

[0040] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 5 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 450°C with the furnace, keep it warm for 2 hours, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy, and finally obtain a high-purity and high-permeability NiPt alloy target.

[0041] Example 4

[0042] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 90:10, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1575°C for 25 minutes.

[0043] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 1150° C. with the furnace, and the temperature is kept for 1 hour. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0044] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -3 Pa, then the temperature and pressure are raised to 1250℃, at which time the pressure is 75MPa, and the temperature and pressure are maintained for 3h before hot pressing into a cylindrical shape;

[0045] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 5 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 450°C with the furnace, keep it warm for 2 hours, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy, and finally obtain a high-purity and high-permeability NiPt alloy target.

[0046] Example 5

[0047] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 90:10, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1575°C for 25 minutes.

[0048] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 950° C. with the furnace, and the temperature is kept for 4 hours. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0049] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -3 Pa, then the temperature and pressure are raised to 1250℃, at which time the pressure is 75MPa, and the temperature and pressure are maintained for 3h before hot pressing into a cylindrical shape;

[0050] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 5 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 450°C with the furnace, keep it warm for 2 hours, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy, and finally obtain a high-purity and high-permeability NiPt alloy target.

[0051] Example 6

[0052] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 90:10, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1575°C for 25 minutes.

[0053] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 1050° C. with the furnace, and the temperature is kept for 2 hours. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0054] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -2 Pa, then the temperature and pressure are raised to 1400°C, at which time the pressure is 100 MPa, and after maintaining the temperature and pressure for 2 hours, hot pressing is performed into a cylindrical shape;

[0055] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 6 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 550°C with the furnace, keep it warm for 1 hour, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy, and finally obtain a high-purity and high-permeability NiPt alloy target.

[0056] Example 7

[0057] Step 1: Using nickel with a purity of 99.9999% and platinum with a purity of 99.999% as raw materials, the atomic ratio of nickel to platinum is 90:10, and smelting them into NiPt alloy ingots in a magnetic levitation melting furnace at a temperature of 1575°C for 25 minutes.

[0058] Step 2: After cooling, the molten ingot of step 1 is taken out and placed in a vacuum heat treatment furnace. After evacuation, the temperature is raised to 1050° C. with the furnace, and the temperature is kept for 2 hours. Then, liquid argon is sprayed into the furnace chamber to cool the ingot into a NiPt alloy ingot.

[0059] Step 3: Place the NiPt alloy ingot in a vacuum hot press and evacuate to 10 -2 After 1000 ℃, the temperature and pressure are increased to 1100℃, at which time the pressure is 50MPa, and the temperature and pressure are maintained for 4 hours before hot pressing into a cylindrical shape;

[0060] Step 4: Cut the hot-pressed NiPt alloy ingot into discs with a thickness of 3.5 mm; perform multiple cold rolling processes on the disc-shaped NiPt alloy on a rolling mill, and perform a vacuum annealing process between two cold rolling deformations; the thickness of the cold-rolled NiPt alloy ingot is the thickness of the finished product + processing allowance; place the cold-rolled NiPt alloy in a vacuum heat treatment furnace, evacuate the vacuum, heat it to 350°C with the furnace, keep it warm for 3 hours, and then turn off the power to cool it; perform surface processing on the heat-treated NiPt alloy to finally obtain a high-purity and high-permeability NiPt alloy target.

[0061] Comparative Example 1

[0062] The specific experimental steps are substantially the same as those in Example 1, except that in step 1, the smelting method adopted is general induction smelting.

[0063] Comparative Example 2

[0064] The specific experimental steps are substantially the same as those of Example 1, except that after step 1, vacuum heat treatment is not performed, and the ingot is directly subjected to vacuum hot pressing.

[0065] Comparative Example 3

[0066] The specific experimental steps are substantially the same as those in Example 1, except that in step 3, the forming method is a general forging method.

[0067] Performance Testing

[0068] Metallic impurity elements were detected by glow discharge mass spectrometry (GDMS);

[0069] Gas elements are detected using a LECO gas detector;

[0070] PTF testing is measured according to ASTMF2086-01 standard;

[0071] The samples prepared in the embodiments and comparative examples were tested, and the specific test results are shown in Table 1 and Table 2.

[0072] Table 1 Main impurity content of NiPt alloy target

[0073]

[0074] Table 2 NiPt alloy target material performance data

[0075]

[0076] Conclusion Analysis

[0077] It can be concluded from the data of Examples 1 to 7 that the use of magnetic suspension melting technology can greatly improve the purity of the finished target material, with a purity of ≥99.999%, and extremely low content of each impurity element, among which the content of metal elements is as low as below 0.1ppm. In addition, the average grain size of the finished target material is also around 60μm, and the component distribution is very uniform, and the final magnetic permeability is maintained at around 75%; the various properties of the finished target material are excellent, reaching a relatively high level in the industry.

[0078] Comparative Example 1 is based on Example 1, and the melting method adopted is general induction melting instead of magnetic levitation melting. It can be seen from the data that the impurity content in the finished target material has increased, especially the C element, which has increased from 5ppm to 54ppm. The main reason is that in general induction melting, the material will be in full contact with the crucible, which is very easy to introduce impurities, while magnetic levitation melting can avoid this problem.

[0079] Comparative Example 2 is based on Example 1, but the vacuum heat treatment operation is cancelled and vacuum hot pressing is directly performed. Compared with the data of Example 1, it is found that without vacuum heat treatment, the residual thermal stress caused by smelting cannot be eliminated, resulting in uneven composition and very serious composition segregation. The deviation rate in various places reaches ±1.3%. At the same time, the grains cannot be refined, and the average grain size is as high as 89μm, which ultimately results in a low magnetic permeability of only 63%.

[0080] Comparative Example 3, based on Example 1, adopts general forging instead of vacuum hot pressing. It is very easy to crack and oxidize during the forging process, and the impurity content of C, N, and O elements in the finished target material is very high. In addition, the forging method cannot further refine the grains. The average grain size of the finished target material is 102μm, compared with 62μm in Example 1, the difference is nearly 40%. Excessively large grains will be detrimental to the transmission of the target material to the magnetic field, resulting in a final magnetic permeability of only 51.2%.

[0081] 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 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, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a nickel-platinum alloy target, characterized in that: The specific steps include: Step 1: Magnetic levitation smelting, smelting the raw materials nickel and platinum into NiPt alloy ingots in a magnetic levitation smelting furnace; Step 2: performing vacuum heat treatment on the NiPt alloy ingot obtained in step 1; Step 3: performing vacuum hot pressing operation on the NiPt alloy ingot after vacuum heat treatment; Step 4: The NiPt alloy ingot obtained by hot pressing is cut into disc shapes, the disc-shaped NiPt alloy ingot is subjected to multiple cold rolling processes, and then subjected to vacuum recrystallization heat treatment, and finally machined to obtain a NiPt alloy target.

2. The preparation method according to claim 1, characterized in that: The purity of the raw nickel and raw platinum described in step 1 is ≥99.9999%, and the atomic ratio of nickel to platinum is 80-95:5-20.

3. The preparation method according to claim 1, characterized in that: The magnetic suspension melting temperature is 1500-1650°C, and the melting time is 15-35 minutes.

4. The preparation method according to claim 1, characterized in that: The vacuum heat treatment operation temperature in step 2 is 950-1150° C., the treatment time is 1-4 hours, and the cooling method is liquid argon cooling.

5. The preparation method according to claim 1, characterized in that: The vacuum degree of the vacuum hot pressing operation described in step 3 is 10 -3 ~10 -2 Pa, temperature is 1100-1400℃, pressure is 50-100MPa, and vacuum hot pressing time is 2-4h.

6. The preparation method according to claim 1, characterized in that: The disc-shaped NiPt alloy described in step 4 has a thickness of 3.5 to 6 mm.

7. The preparation method according to claim 1, characterized in that: The vacuum recrystallization heat treatment temperature in step 4 is 350-550° C. and the time is 1-3 hours.

8. A nickel-platinum alloy target material prepared by the preparation method according to any one of claims 1 to 7.

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