Nickel-iron alloy target material as well as preparation method and application thereof

Abstract

The invention relates to a nickel-iron alloy target material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing nickel powder and iron powder to obtain mixed powder; and (2) the mixed powder obtained in the step (1) is subjected to compaction treatment and vacuum hot pressing sintering treatment in sequence, and the nickel-iron alloy target material is obtained, wherein the vacuum hot pressing sintering treatment comprises first pressurizing treatment, first heating treatment, first heat preservation and pressure maintaining treatment, second heating treatment and second pressurizing treatment which are sequentially carried out. The nickel-iron alloy target material which is high in density, uniform in microstructure, uniform in component and excellent in machining performance is prepared by adopting a special sintering process.

Description

Technical Field

[0001] This invention relates to the field of sputtering target technology, and in particular to a nickel-iron alloy target, its preparation method, and its application. Background Technology

[0002] Nickel-iron alloy sputtering targets are widely used materials in the field of magnetron sputtering, possessing excellent physical and chemical properties, including hardness, strength, electrical and thermal conductivity, as well as corrosion resistance and oxidation resistance. It is a low-frequency soft magnetic material with high permeability and low coercivity in weak magnetic fields. It is typically manufactured by forging, rolling, heat treatment, and machining ingots obtained through high-vacuum melting. However, existing methods for preparing nickel-iron alloy sputtering targets have some problems. Targets prepared by traditional plastic deformation processes after melting and casting often have uneven internal structures and contain small defects, affecting the normal sputtering performance.

[0003] CN105463395A discloses a high-performance nickel-iron alloy sputtering target and its preparation method. The preparation method includes the following steps: (1) Hot forging: The purity of the nickel-iron alloy ingot is 4N or higher, and the atomic ratio of Ni to Fe is 45:55; the nickel-iron alloy ingot is hot-forged into a billet, and the heating temperature is 1200℃; (2) Rolling: the hot-forged billet is cold-rolled to thin the billet and refine the grains, and two rolling processes are performed; the deformation amount in the first rolling is 60%, and the total deformation amount in the second rolling is 80%. The rolling direction can be unidirectional rolling or cross rolling according to the shape of the target material; (3) Intermediate heat treatment: the billet is subjected to intermediate heat treatment between two cold rollings at a temperature of 700℃ to eliminate work hardening; (4) Recrystallization heat treatment: the billet after final rolling is subjected to recrystallization heat treatment at a temperature of 850℃ to make the structure completely recrystallize; (5) Deformation: the billet after recrystallization heat treatment is subjected to rolling deformation with a total deformation of 10%; (6) Finishing of finished product: the billet is processed into the required specifications to obtain nickel-iron alloy sputtering target material. Although it can obtain high-performance nickel-iron alloy sputtering target material with uniform structure, the average grain size is between 20μm and 100μm, and the sputtering surface of the target material has an irregular crystal orientation.

[0004] Therefore, developing a novel method for preparing nickel-iron alloy targets that can improve the density of the target material, reduce the average particle size of the nickel phase, and solve the problems of structural inhomogeneity and defects in existing technologies has become an important topic in the current technological field. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a nickel-iron alloy target material, its preparation method and application, which is prepared by a special sintering process to obtain a nickel-iron alloy target material with high density, uniform microstructure, uniform composition and excellent machinability.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a nickel-iron alloy target, the method comprising the following steps:

[0008] (1) Mix nickel powder and iron powder to obtain a mixed powder;

[0009] (2) The mixed powder in step (1) is subjected to compaction and vacuum hot pressing sintering in sequence to obtain the nickel-iron alloy target material;

[0010] The vacuum hot pressing sintering process includes a first pressurization process, a first heating process, a first heat preservation and pressure holding process, a second heating process, and a second pressurization process performed sequentially.

[0011] This invention first compacts the mixed powder to avoid internal pores that would result in low density; then it performs vacuum hot pressing sintering and controls the process steps of vacuum hot pressing sintering to prepare a nickel-iron alloy target with high density, compliant appearance and dimensions, and excellent internal structure. The nickel-iron alloy target prepared by this invention meets the high performance requirements as a sputtering target.

[0012] As a preferred technical solution of the present invention, the mass ratio of nickel powder to iron powder in step (1) is 1:(0.3~1), for example, it can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.8 or 1:1, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0013] Preferably, the average particle size of the nickel powder is 1~5μm, for example, it can be 1μm, 2μm, 3μm, 4μm or 5μm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0014] Preferably, the purity of the nickel powder is ≥99.95%, for example, it can be 99.95%, 99.96%, 99.97%, 99.98% or 99.99%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0015] Preferably, the average particle size of the iron powder is <10μm, for example, it can be 5μm, 6μm, 7μm, 8μm or 9μm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0016] Preferably, the purity of the iron powder is ≥99.99%, for example, it can be 99.99%, 99.991%, 99.992%, 99.993%, 99.994% or 99.995%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] This invention improves the mixing uniformity and compaction density of the mixed powder by selecting the particle size and reasonable gradation of the two raw material powders, reduces the dimensional shrinkage rate during sintering, and successfully prepares a nickel-iron alloy target material with high density, uniform microstructure and composition by using a special vacuum hot pressing sintering treatment.

[0018] Preferably, the mixing is carried out in a protective gas.

[0019] Preferably, the protective gas includes any one of argon, nitrogen, or helium.

[0020] In this invention, the mixing is carried out in a protective gas to prevent the gas from affecting the purity of the powder, thereby reducing the purity of the obtained nickel-iron alloy target.

[0021] Preferably, the mixing is carried out in a three-dimensional powder mixer.

[0022] Preferably, the rotational speed of the three-dimensional powder mixer is 20~50 r / min, for example, it can be 20 r / min, 25 r / min, 30 r / min, 35 r / min, 40 r / min or 50 r / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0023] Preferably, the material-to-ball ratio in the mixing process is 10:(1~3), for example, it can be 10:1, 20:3, 5:1, 4:1 or 10:3, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] Preferably, the mixing time is ≥48h, for example, it can be 48h, 49h, 50h, 51h or 52h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0025] This invention limits the mixing time to ≥48h to ensure that the nickel powder and iron powder are mixed evenly and without large particle agglomeration.

[0026] Preferably, the mixing balls in the mixing process include hard zirconium balls and / or zirconium oxide balls.

[0027] As a preferred technical solution of the present invention, the compaction process in step (2) is: the mixed powder is loaded into a mold and compacted.

[0028] In this invention, the mold is a graphite mold; after compaction, it is placed in a vacuum sintering furnace, and the mold is placed in a horizontal position.

[0029] Preferably, the pressure of the first pressurization process is 5 to 20t, for example, it can be 5t, 10t, 15t or 20t, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0030] This invention involves a first pressurization process after compacting the mixed powder, with the pressure controlled at 5-20t. This ensures close contact between the mixed powder particles, reduces porosity, provides a more uniform matrix for subsequent processing, and prevents the segregation of nickel and iron in the mixed powder due to density differences during subsequent heat treatment. If the pressure of the first pressurization process is less than 5t, insufficient contact between particles will result in high porosity and low density in the final nickel-iron alloy target. If the pressure of the first pressurization process is greater than 20t, residual stress will exist inside the green blank, which will cause internal cracks in the nickel-iron alloy target during subsequent heat treatment.

[0031] Preferably, the holding time of the first pressurization process is 2 to 10 minutes, for example, it can be 2 minutes, 4 minutes, 6 minutes, 8 minutes or 10 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0032] Preferably, the process between the first pressurization process and the first heating process further includes: evacuating to a vacuum level of <100Pa, for example, 50Pa, 60Pa, 70Pa, 80Pa or 90Pa, but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0033] Preferably, the heating rate of the first heating process is 5~10℃ / min, for example, it can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0034] Preferably, the endpoint temperature of the first heating process is 900~1000℃, for example, it can be 900℃, 920℃, 940℃, 960℃, 980℃ or 1000℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0035] This invention controls the process steps of vacuum hot pressing sintering and limits the endpoint temperature of the first heating treatment to prepare nickel-iron alloy targets with high density, compliant appearance and size, and excellent internal structure. If the endpoint temperature of the first heating treatment is too low, the small pore shrinkage will result in a large number of pores, causing a decrease in the density of the obtained nickel-iron alloy target. If the endpoint temperature of the first heating treatment is too high, the grains will grow significantly, causing the pores to not be able to escape in time, resulting in large micro-grain size and intergranular pores in the obtained nickel-iron alloy target, thus reducing the density.

[0036] Preferably, when the pressure during the first heating process is >50t, a depressurization process is performed.

[0037] It should be noted that in this invention, the thermal expansion of the mixed powder during the heating process will cause the pressure inside the mold to increase. Therefore, in order to maintain pressure stability, when the pressure exceeds 50t, pressure relief is required. Multiple pressure relief processes may be performed during the heating process.

[0038] As a preferred technical solution of the present invention, the temperature of the first heat preservation and pressure treatment in step (2) is 900~1000℃, for example, it can be 900℃, 920℃, 940℃, 960℃, 980℃ or 1000℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0039] Preferably, the pressure of the first heat preservation and pressure treatment is 45~50t, for example, it can be 45t, 46t, 47t, 48t, 49t or 50t, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0040] Preferably, the first heat preservation and pressure holding time is 60 to 90 minutes, for example, it can be 60 minutes, 70 minutes, 80 minutes or 90 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0041] In this invention, the first heat preservation and pressure holding treatment is to ensure that the nickel-iron alloy billet is fully heated. Therefore, expansion will still occur during this process. By controlling the temperature, pressure and time of the first heat preservation and pressure holding treatment within a reasonable range, this invention can improve the density of the prepared nickel-iron alloy target material.

[0042] As a preferred technical solution of the present invention, the heating rate of the second heating process in step (2) is 1~5℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0043] Preferably, the endpoint temperature of the second heating process is 1100~1200℃, for example, it can be 1100℃, 1120℃, 1140℃, 1160℃, 1180℃ or 1200℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0044] This invention controls the process steps of vacuum hot pressing sintering and limits the endpoint temperature of the second heating treatment to prepare nickel-iron alloy targets with high density, compliant appearance and dimensions, and excellent internal structure. If the endpoint temperature of the second heating treatment is too low, a large number of pores will be generated due to small pore shrinkage, resulting in a decrease in the density of the obtained nickel-iron alloy target. If the endpoint temperature of the second heating treatment is too high, it will lead to significant grain growth, resulting in an uneven internal structure of the obtained nickel-iron alloy target and a decrease in density.

[0045] Preferably, the holding time for the second heating treatment is ≥1h, for example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0046] Preferably, when the pressure during the second heating process is >50t, a depressurization process is performed.

[0047] As a preferred technical solution of the present invention, step (2) the second pressurization process is: pressurizing to 280~320t within 2~4h. The time required for the second pressurization process is 2~4h, for example, it can be 2h, 2.5h, 3h, 3.5h or 4h. The final pressure of the second pressurization process is 280~320t, for example, it can be 280t, 290t, 300t, 310t or 320t, but it is not limited to the listed values. Other unlisted values ​​within the above value range are also applicable.

[0048] This invention controls the process steps of vacuum hot pressing sintering and limits the final pressure of the second pressurization process to prepare nickel-iron alloy targets with high density, compliant appearance and size, and excellent internal structure. If the final pressure of the second pressurization process is too low, it will not be conducive to the reduction of pores between powders, resulting in a decrease in the density of the obtained nickel-iron alloy targets; if the final pressure of the second pressurization process is too high, it will cause internal cracks in the nickel-iron alloy targets.

[0049] Preferably, the second pressurization process further includes a depressurization process and furnace cooling performed sequentially.

[0050] Preferably, the depressurization process involves introducing the protective gas to a furnace pressure of -0.06 to -0.08 MPa, such as -0.06 MPa, -0.065 MPa, -0.07 MPa, -0.075 MPa, or -0.08 MPa, but is not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0051] Preferably, the final temperature of the furnace cooling is <200°C, for example, it can be 175°C, 180°C, 185°C, 190°C or 195°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0052] In this invention, after the furnace is cooled to <200°C, the mold and target blank are removed and air-cooled to room temperature.

[0053] Preferably, the vacuum hot pressing sintering process further includes machining.

[0054] Preferably, the machining process includes grinding and / or wire cutting.

[0055] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0056] (1) Nickel powder with an average particle size of 1~5 μm and iron powder with an average particle size of <10 μm are mixed in a protective gas at a mass ratio of 1:(0.3~1) to obtain a mixed powder;

[0057] (2) The mixed powder described in step (1) is loaded into a mold and compacted, and then vacuum hot pressing sintering and machining are performed in sequence to obtain the nickel-iron alloy target material;

[0058] The vacuum hot-pressing sintering process includes the following sequential processes: a first pressurization process with a pressure of 5-20t and a holding time of 2-10min; after evacuating to a vacuum degree of <100Pa, a first heating process with a heating rate of 5-10℃ / min to 900-1000℃; a first holding and pressurizing process with a temperature of 900-1000℃, a pressure of 45-50t, and a time of 60-90min; a second heating process with a heating rate of 1-5℃ / min to 1100-1200℃ and a holding time of ≥1h; a second pressurization process with a pressure of 280-320t over 2-4h; and finally, a protective gas is introduced to a furnace pressure of -0.06--0.08MPa for depressurization, followed by cooling with the furnace to <200℃.

[0059] When the pressure in the first heating process and the second heating process is greater than 50t, pressure relief is performed.

[0060] In a second aspect, the present invention provides a nickel-iron alloy target material, which is prepared by the preparation method described in the first aspect.

[0061] The nickel-iron alloy target of the present invention has high density, uniform microstructure, uniform composition and excellent machinability.

[0062] As a preferred embodiment of the present invention, the nickel-iron alloy target material contains 50-76% nickel by mass, with the remainder being iron. The nickel content in the target material can be 50-76% by mass, for example, 50%, 55%, 60%, 65%, 70%, or 76%, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0063] Thirdly, the present invention provides an application of the nickel-iron alloy target according to the second aspect, wherein the nickel-iron alloy target is used for magnetron sputtering.

[0064] Compared with the prior art, the present invention has at least the following beneficial effects:

[0065] This invention employs a special sintering process to prepare nickel-iron alloy targets with high density, uniform microstructure, uniform composition, and excellent machinability. The density of the nickel-iron alloy targets can reach over 99.4%, and the average particle size of the nickel phase can be controlled within 35 μm. Detailed Implementation

[0066] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0067] Example 1

[0068] This embodiment provides a nickel-iron alloy target and its preparation method, wherein the nickel-iron alloy target has a nickel mass percentage of 50% and an iron mass percentage of 50%.

[0069] The preparation method includes the following steps:

[0070] (1) Nickel powder with an average particle size of 3 μm and a purity of 99.95% and iron powder with an average particle size of 6 μm and a purity of 99.99% are mixed in argon gas at a mass ratio of 1:1 to obtain a mixed powder; the mixing is carried out in a three-dimensional powder mixer with a rotation speed of 40 r / min, a material-to-particle ratio of 5:1 and a time of 50 h; and the powder mixing balls used in the mixing process are hard zirconium balls;

[0071] (2) The mixed powder described in step (1) is loaded into a graphite mold and compacted. After compaction, it is placed in a vacuum sintering furnace. After placement, the mold is kept in a horizontal position. Then, vacuum hot pressing sintering and grinding are performed in sequence to obtain the nickel-iron alloy target material.

[0072] The vacuum hot pressing sintering process includes the following sequential processes: a first pressurization process with a pressure of 10t and a holding time of 6min; after evacuating to a vacuum degree of 70Pa, the temperature is increased to 950℃ at a heating rate of 7℃ / min for a first heating process; then a first heat holding and pressure holding process with a temperature of 950℃, a pressure of 48t, and a time of 80min is performed; subsequently, the temperature is increased to 1150℃ at a heating rate of 3℃ / min for a second heating process and held for 2h; then, the pressure is increased to 300t within 3h for a second pressurization process; finally, argon gas is introduced to reduce the pressure inside the furnace to -0.07MPa for depressurization, and the furnace is cooled to 185℃. The mold and target blank are then removed and air-cooled to 25℃.

[0073] When the pressure in the first heating process and the second heating process is greater than 50t, pressure relief is performed.

[0074] Example 2

[0075] This embodiment provides a nickel-iron alloy target and its preparation method, wherein the nickel-iron alloy target has a nickel mass percentage of 60% and an iron mass percentage of 40%.

[0076] The preparation method includes the following steps:

[0077] (1) Nickel powder with an average particle size of 4 μm and a purity of 99.95% and iron powder with an average particle size of 7 μm and a purity of 99.99% were mixed in nitrogen at a mass ratio of 3:2 to obtain a mixed powder; the mixing was carried out in a three-dimensional powder mixer with a rotation speed of 35 r / min, a material-to-particle ratio of 10:1 and a time of 48 h; and the powder mixing balls used in the mixing process were zirconia balls;

[0078] (2) The mixed powder described in step (1) is loaded into a graphite mold and compacted. After compaction, it is placed in a vacuum sintering furnace. After placement, the mold is kept in a horizontal position. Then, vacuum hot pressing sintering and wire cutting are performed in sequence to obtain the nickel-iron alloy target material.

[0079] The vacuum hot pressing sintering process includes the following sequential processes: a first pressurization process with a pressure of 5t and a holding time of 10min; after evacuating to a vacuum degree of 90Pa, the temperature is increased to 1000℃ at a heating rate of 10℃ / min for a first heating process; then a first heat holding and pressure holding process with a temperature of 1000℃, a pressure of 50t, and a time of 60min is performed; subsequently, the temperature is increased to 1100℃ at a heating rate of 1℃ / min for a second heating process and held for 3h; then, the pressure is increased to 280t within 2h for a second pressurization process; finally, argon gas is introduced to reduce the pressure inside the furnace to -0.06MPa for a depressurization process, and the furnace is cooled to 195℃. The mold and target blank are then removed and air-cooled to 25℃.

[0080] When the pressure in the first heating process and the second heating process is greater than 50t, pressure relief is performed.

[0081] Example 3

[0082] This embodiment provides a nickel-iron alloy target and its preparation method, wherein the nickel-iron alloy target has a nickel mass percentage of 75% and an iron mass percentage of 25%.

[0083] The preparation method includes the following steps:

[0084] (1) Nickel powder with an average particle size of 5 μm and a purity of 99.95% and iron powder with an average particle size of 9 μm and a purity of 99.99% were mixed in argon gas at a mass ratio of 3:1 to obtain a mixed powder; the mixing was carried out in a three-dimensional powder mixer with a rotation speed of 50 r / min, a material-to-particle ratio of 10:3 and a time of 52 h; and the powder mixing balls used in the mixing process were zirconia balls;

[0085] (2) The mixed powder described in step (1) is loaded into a graphite mold and compacted. After compaction, it is placed in a vacuum sintering furnace. After placement, the mold is kept in a horizontal position. Then, vacuum hot pressing sintering and grinding are performed in sequence to obtain the nickel-iron alloy target material.

[0086] The vacuum hot pressing sintering process includes the following sequential processes: a first pressurization process with a pressure of 20t and a holding time of 2min; after evacuating to a vacuum degree of 50Pa, the temperature is increased to 900℃ at a heating rate of 5℃ / min for a first heating process; then a first heat holding and pressure holding process with a temperature of 900℃, a pressure of 45t, and a time of 90min is performed; subsequently, the temperature is increased to 1200℃ at a heating rate of 5℃ / min for a second heating process and held for 1h; then, the pressure is increased to 320t within 4h for a second pressurization process; finally, argon gas is introduced to reduce the pressure inside the furnace to -0.08MPa for depressurization, and the furnace is cooled to 175℃. The mold and target blank are then removed and air-cooled to 25℃.

[0087] When the pressure in the first heating process and the second heating process is greater than 50t, pressure relief is performed.

[0088] Example 4

[0089] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the pressure of the first pressurization process in step (2) is adjusted from 10t to 2t, while the rest is the same as in Embodiment 1.

[0090] Example 5

[0091] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the pressure of the first pressurization process in step (2) is adjusted from 10t to 30t, while the rest is the same as in Embodiment 1.

[0092] Example 6

[0093] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the final temperature of the first heating treatment in step (2) is adjusted from 950°C to 800°C. All other aspects are the same as in Embodiment 1.

[0094] Example 7

[0095] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the endpoint temperature of the first heating treatment in step (2) is adjusted from 950°C to 1050°C. All other aspects are the same as in Embodiment 1.

[0096] Example 8

[0097] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the endpoint temperature of the second heating treatment in step (2) is adjusted from 1150℃ to 1050℃. All other aspects are the same as in Embodiment 1.

[0098] Example 9

[0099] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the endpoint temperature of the second heating treatment in step (2) is adjusted from 1150℃ to 1300℃. All other aspects are the same as in Embodiment 1.

[0100] Example 10

[0101] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the final pressure of the second pressurization process in step (2) is adjusted from 300t to 250t. All other aspects are the same as in Embodiment 1.

[0102] Example 11

[0103] This embodiment provides a nickel-iron alloy target and its preparation method. The only difference from Embodiment 1 is that the final pressure of the second pressurization process in step (2) is adjusted from 300t to 350t. All other aspects are the same as in Embodiment 1.

[0104] Comparative Example 1

[0105] This comparative example provides a nickel-iron alloy target and its preparation method. The only difference between this example and Example 1 is that, except for step (2), which does not include compaction treatment, the rest is the same as Example 1.

[0106] Comparative Example 2

[0107] This comparative example provides a nickel-iron alloy target and its preparation method. The only difference between this example and Example 1 is that, except for step (2), which does not include the second heating treatment, all other steps are the same as in Example 1.

[0108] Comparative Example 3

[0109] This comparative example provides a nickel-iron alloy target and its preparation method. The only difference between this example and Example 1 is that, except for step (2), which does not include the second pressurization treatment, the rest is the same as Example 1.

[0110] Comparative Example 4

[0111] This comparative example provides a nickel-iron alloy target and its preparation method, which differs from Example 1 only in that the preparation method includes the following steps:

[0112] (1) In an argon atmosphere, nickel powder and iron powder are mixed to obtain a pre-alloyed powder;

[0113] (2) The pre-alloyed powder described in step (1) is loaded into a polyurethane sleeve and cold isostatically pre-pressed. After demolding, it is vacuum sintered at 450°C for 6 hours.

[0114] The cold isostatic pressing pre-pressing process is carried out at a pressure of 250 MPa for 30 minutes.

[0115] (3) The target blank block after vacuum sintering in step (2) is subjected to hot isostatic pressing to obtain the nickel-iron alloy target material;

[0116] The hot isostatic pressing temperature was 750°C, the holding time was 3 hours, and the pressure was 195 MPa. All other conditions were the same as in Example 1.

[0117] The density, internal microstructure, and average particle size of the nickel phase of the nickel-iron alloy targets prepared in Examples 1-11 and Comparative Examples 1-4 were tested. The density was tested using the Archimedes displacement method. The internal microstructure was tested using scanning electron microscopy and classified into three levels according to the uniformity: Level I for uniform internal microstructure, Level II for relatively uniform internal microstructure, and Level III for non-uniform internal microstructure. The average particle size of the nickel phase was also tested using scanning electron microscopy. The test results are shown in Table 1.

[0118] Table 1

[0119]

[0120] The test results show that:

[0121] (1) As can be seen from Examples 1 to 3, by setting up multiple stages of pressurization, heating and heat preservation in the vacuum hot pressing sintering process, and by controlling various process parameters, the present invention produces nickel-iron alloy targets with high purity and density, uniform internal structure, and the average particle size of nickel phase can be controlled within 35 μm.

[0122] (2) As can be seen from Examples 1 and 4-5, in Example 1, the pressure of the first pressurization treatment in step (2) is 10t, and the density of the nickel-iron alloy target material prepared is 99.8%, the internal structure is uniform, and the average particle size of the nickel phase is 32μm; while in Example 4, the pressure of the first pressurization treatment in step (2) is 2t, and the density of the nickel-iron alloy target material prepared is 96.3%, the internal structure is non-uniform, and the average particle size of the nickel phase is 35μm; in Example 5, the pressure of the first pressurization treatment in step (2) is 30t, and the density of the nickel-iron alloy target material prepared is 97.6%, the internal structure is non-uniform, and the average particle size of the nickel phase is 40μm. This shows that the present invention continues to perform the first pressurization treatment after compacting the mixed powder and controls the pressure to 5~20t to prevent gaps or excessive compaction between the mixed powder particles, so as to avoid the formation of stubborn pores that are extremely difficult to completely eliminate during sintering, forming macroscopic defects, and ultimately leading to severe uneven densification.

[0123] (3) As can be seen from Examples 1 and 6-9, in Example 1, the final temperature of the first heating treatment in step (2) is 950℃ and the final temperature of the second heating treatment is 1150℃. The resulting nickel-iron alloy target has a density of 99.8% and a uniform internal structure. In Example 6, the final temperature of the first heating treatment in step (2) is 800℃. The resulting nickel-iron alloy target has a density of 95.4% and a relatively uniform internal structure. In Example 7, the final temperature of the first heating treatment in step (2) is 1050℃. The resulting nickel-iron alloy target has a density of 96.7% and a relatively uniform internal structure. In Example 8, the endpoint temperature of the second heating treatment in step (2) was 1050℃, and the density of the nickel-iron alloy target material prepared there was 98.6%, with a relatively uniform internal structure. In Example 9, the endpoint temperature of the second heating treatment in step (2) was 1300℃, and the density of the nickel-iron alloy target material prepared there was 98.2%, with a relatively uniform internal structure. This shows that the endpoint temperatures of the first and second heating treatments have a significant impact on the density and internal structure uniformity of the nickel-iron alloy target material. Temperatures that are too low or too high will result in the target material not meeting the required density and poor sputtering performance. Therefore, it is necessary to strictly control the range of temperature selection.

[0124] (4) As can be seen from Examples 1 and 10-11, the final pressure of the second pressurization treatment in step (2) of Example 1 is 300t, and the density of the nickel-iron alloy target material prepared is 99.8%, the internal structure is uniform, and the average particle size of the nickel phase is 32μm; while the final pressure of the second pressurization treatment in step (2) of Example 10 is 250t, and the density of the nickel-iron alloy target material prepared is 97.5%, the internal structure is relatively uniform, and the average particle size of the nickel phase is 43μm; the final pressure of the second pressurization treatment in step (2) of Example 11 is 350t, and the density of the nickel-iron alloy target material prepared is 98.4%, the internal structure is relatively uniform, and the average particle size of the nickel phase is 42μm. This shows that insufficient final pressure of the second pressurization treatment will lead to insufficient densification, more residual pores, and coarsening of grains. Excessive pressure will lead to abnormal grain growth and deformation, and will also aggravate mold wear, shorten mold life, and increase costs.

[0125] (5) As can be seen from Example 1 and Comparative Examples 1-4, the present invention uses a special sintering process to prepare nickel-iron alloy targets with high density, uniform grains and excellent sputtering performance.

[0126] In summary, this invention employs a special sintering process to prepare nickel-iron alloy targets with high density, uniform microstructure, uniform composition, and excellent machinability. The density of the nickel-iron alloy targets can reach over 99.4%, and the average particle size of the nickel phase can be controlled within 35 μm.

[0127] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a nickel-iron alloy target, characterized in that, The preparation method includes the following steps: (1) Mix nickel powder and iron powder to obtain a mixed powder; (2) The mixed powder in step (1) is subjected to compaction and vacuum hot pressing sintering in sequence to obtain the nickel-iron alloy target material; The vacuum hot pressing sintering process includes a first pressurization process, a first heating process, a first heat preservation and pressure holding process, a second heating process, and a second pressurization process performed sequentially.

2. The preparation method according to claim 1, characterized in that, The mass ratio of nickel powder to iron powder in step (1) is 1:(0.3~1); Preferably, the average particle size of the nickel powder is 1~5μm; Preferably, the purity of the nickel powder is ≥99.95%; Preferably, the average particle size of the iron powder is <10 μm; Preferably, the purity of the iron powder is ≥99.99%; Preferably, the mixing is carried out in a protective gas; Preferably, the protective gas includes any one of argon, nitrogen, or helium; Preferably, the mixing is carried out in a three-dimensional powder mixer; Preferably, the ratio of material to pellets in the mixing process is 10:(1~3); Preferably, the mixing time is ≥48h.

3. The preparation method according to claim 1 or 2, characterized in that, The compaction process in step (2) is as follows: the mixed powder is loaded into a mold and compacted; Preferably, the pressure of the first pressurization process is 5~20t; Preferably, the holding time for the first pressurization process is 2 to 10 minutes; Preferably, the process between the first pressurization treatment and the first heating treatment further includes: evacuating to a vacuum level of <100 Pa; Preferably, the heating rate of the first heating treatment is 5~10℃ / min; Preferably, the final temperature of the first heating treatment is 900~1000℃; Preferably, when the pressure during the first heating process is >50t, a depressurization process is performed.

4. The preparation method according to any one of claims 1-3, characterized in that, In step (2), the temperature of the first heat preservation and pressure treatment is 900~1000℃; Preferably, the pressure of the first heat preservation and pressure holding treatment is 45~50t; Preferably, the first heat preservation and pressure holding treatment time is 60~90 minutes.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the heating rate of the second heating treatment is 1~5℃ / min; Preferably, the final temperature of the second heating treatment is 1100~1200℃; Preferably, the heat preservation time of the second heating treatment is ≥1 hour; Preferably, when the pressure during the second heating process is >50t, a depressurization process is performed.

6. The preparation method according to claim 2, characterized in that, Step (2) The second pressurization process is to pressurize to 280-320t within 2-4 hours; Preferably, the second pressurization process further includes a depressurization process and furnace cooling performed sequentially. Preferably, the depressurization process involves introducing the protective gas until the furnace pressure reaches -0.06 to -0.08 MPa. Preferably, the final temperature of the furnace cooling is <200°C; Preferably, the vacuum hot pressing sintering process is followed by machining. Preferably, the machining process includes grinding and / or wire cutting.

7. The preparation method according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Nickel powder with an average particle size of 1~5 μm and iron powder with an average particle size of <10 μm are mixed in a protective gas at a mass ratio of 1:(0.3~1) to obtain a mixed powder; (2) The mixed powder described in step (1) is loaded into a mold and compacted, and then vacuum hot pressing sintering and machining are performed in sequence to obtain the nickel-iron alloy target material; The vacuum hot-pressing sintering process includes the following sequential processes: a first pressurization process with a pressure of 5-20t and a holding time of 2-10min; after evacuating to a vacuum degree of <100Pa, a first heating process with a heating rate of 5-10℃ / min to 900-1000℃; a first holding and pressurizing process with a temperature of 900-1000℃, a pressure of 45-50t, and a time of 60-90min; a second heating process with a heating rate of 1-5℃ / min to 1100-1200℃ and a holding time of ≥1h; a second pressurization process with a pressure of 280-320t over 2-4h; and finally, a protective gas is introduced to a furnace pressure of -0.06--0.08MPa for depressurization, followed by cooling with the furnace to <200℃. When the pressure in the first heating process and the second heating process is greater than 50t, pressure relief is performed.

8. A nickel-iron alloy target material, characterized in that, The nickel-iron alloy target is prepared using the preparation method described in any one of claims 1-7.

9. The nickel-iron alloy target material according to claim 8, characterized in that, The nickel-iron alloy target material contains 50-76% nickel by mass, with the remainder being iron.

10. An application of the nickel-iron alloy target material according to claim 8 or 9, characterized in that, The nickel-iron alloy target is used for magnetron sputtering.

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