Aluminum-scandium target material and preparation method thereof

Abstract

The invention provides an aluminum-scandium target material and a preparation method thereof, and the preparation method comprises the following steps: carrying out hot-pressing heat preservation treatment on a mold in which an aluminum-scandium cast ingot is placed under the condition that the vacuum degree is 10 <-3 >-10 <-2 > Pa, and then carrying out post-treatment to obtain the aluminum-scandium target material, wherein the pressure of the hot pressing heat preservation treatment is 25-60 MPa; the temperature of the hot pressing heat preservation treatment is 610-1200 DEG C; the time of the hot-pressing heat preservation treatment is 2-10 hours; the distance between the side face of the aluminum-scandium cast ingot and the inner wall face of the die is smaller than or equal to 1 mm. The preparation method has the characteristics of short process and low cost, and the prepared aluminum-scandium target material has lower oxygen content, higher relative density and lower internal defects.

Description

Technical Field

[0001] The invention relates to an aluminum-scandium target material and a preparation method thereof. Background Art

[0002] With the rapid iteration of the 5G communication industry, piezoelectric film technology has also achieved rapid development in piezoelectric resonators. Among them, AlN materials have been widely studied due to their high Curie temperature and excellent stability. At the same time, in recent years, people have found that ScAlN films doped with Sc can significantly improve the electromechanical coupling coefficient of the material. When Sc doping reaches 43at.%, Sc 0.43 Al 0.57 Piezoelectric coefficient d of N film 33 It is 5 times that of AlN film, which makes ScAlN an ideal material for MENS and NEMS devices.

[0003] ScAlN (aluminum scandium nitride) film is prepared by sputtering AlSc (aluminum scandium) target in a nitrogen and argon mixed atmosphere, so the preparation effect of aluminum scandium alloy target directly affects the product quality of ScAlN film. The traditional method of preparing aluminum scandium target is to melt pure scandium and pure aluminum in a vacuum melting furnace, and then cast it into aluminum scandium ingot, but its non-negligible internal defects cause its relative density to be too low. Patent CN111455327A mentions that the cast aluminum scandium alloy is ball-milled and vacuum-dried to obtain alloy powder, and then the aluminum scandium target is prepared by powder metallurgy; Patent CN111485207A also atomizes aluminum scandium ingots to make powder; Patent CN111636054A atomizes aluminum scandium molten alloy liquid by inert gas flow. Hot pressing or hot isostatic pressing of aluminum-scandium powder to prepare aluminum-scandium alloy targets can solve the density problem, but the cumbersome process increases production costs and the control of oxygen content in the powder has always been a difficult problem in the preparation of aluminum-scandium targets.

[0004] In view of the problems existing in the above-mentioned methods for producing and preparing aluminum-scandium targets, it is urgent to provide a method for preparing aluminum-scandium targets. Summary of the invention

[0005] In view of the problems that currently occur in the preparation process of aluminum-scandium targets, such as complicated process, insufficient target density, and high cost, the present invention provides a method for preparing an aluminum-scandium target. The preparation method has the characteristics of short process and low cost, and the prepared aluminum-scandium target has lower oxygen content, higher relative density and lower internal defects.

[0006] The present invention provides a method for preparing an aluminum-scandium target, which comprises the following steps:

[0007] The mold containing the aluminum-scandium ingot is placed in a vacuum of 10 -3 ~10 -2Pa, and then undergo post-treatment to obtain an aluminum-scandium target; wherein the pressure of the hot pressing and heat preservation treatment is 25-60 MPa; the temperature of the hot pressing and heat preservation treatment is 610-1200°C; and the time of the hot pressing and heat preservation treatment is 2-10 h;

[0008] The distance between the side surface of the aluminum-scandium ingot and the inner wall surface of the mold is less than or equal to 1 mm.

[0009] In the present invention, the aluminum-scandium ingot is subjected to hot pressing and heat preservation treatment under vacuum conditions, which can effectively remove oxygen impurities in the aluminum-scandium target material, fully ensure the purity of the target material, and thus ensure the quality of the final target sheet.

[0010] In the present invention, by controlling the distance between the side of the aluminum-scandium ingot and the inner wall of the mold, the diameter of the aluminum-scandium target material is kept as small as possible, and the thickness of the target material is reduced due to the action of external pressure, thereby reducing the loose pores inside the target material and approaching the theoretical density of the target material.

[0011] In some embodiments, the hot pressing and heat preservation treatment is performed in a vacuum melting furnace.

[0012] In a specific implementation manner, the pressure inside the vacuum melting furnace is 25-60 Mpa.

[0013] In some embodiments, the temperature of the hot pressing and heat preservation treatment is 610-800°C.

[0014] In a specific embodiment, the temperature of the hot pressing and heat preservation treatment is 630-800°C.

[0015] In some embodiments, the hot pressing and heat preservation treatment further includes a step of gradient temperature increase.

[0016] In a specific embodiment, the gradient heating step includes one-stage heating and two-stage heating.

[0017] In a preferred embodiment, the first stage of heating is to raise the temperature from room temperature to 250°C within 30 minutes, and then keep it warm for 20 minutes; the second stage of heating is to raise the temperature from 250°C to the temperature of the hot pressing and heat preservation treatment within 50 minutes; by controlling the heating method, the heating rate is slowed down, thereby controlling the size of the grains inside the target material.

[0018] In some embodiments, the pressure of the hot pressing and heat preservation treatment is 30-40 MPa.

[0019] In the present invention, pressure needs to be applied during the hot pressing and heat preservation treatment, and the pressure of the hot pressing and heat preservation treatment is controlled to float within the range of ±0.5Mpa; and no pressure needs to be applied in the heating step before the hot pressing and heat preservation treatment.

[0020] In some embodiments, the heat-pressing and heat-insulating treatment time is 2 to 6 h, for example 6 h.

[0021] In some embodiments, the mold contains a cavity, and the shape of the cavity is the same as the shape of the aluminum-scandium ingot; in any cross section, the difference between the radius of the aluminum-scandium ingot and the radius of the inner wall surface of the mold is less than or equal to 1 mm.

[0022] In a specific embodiment, the mold is made of steel or graphite; the steel includes H13 steel.

[0023] In a specific implementation, a protective cover is provided on the periphery of the mold; the material of the protective cover is Q235 steel to prevent damage to the furnace wall and the heating element caused by excessive pressure during the process.

[0024] In a specific embodiment, the mold contains a cylindrical cavity, and the aluminum-scandium ingot is cylindrical; preferably, the cross-sectional diameter of the aluminum-scandium ingot is 3-12 inches; for example, 3 inches, 4 inches, 6 inches, 8 inches or 12 inches.

[0025] In a specific embodiment, the mold contains a cavity in the shape of a square column, and the aluminum-scandium ingot is in the shape of a square column.

[0026] In a specific implementation, steel blocks are respectively attached to the upper and lower surfaces of the aluminum-scandium ingot to ensure that the upper and lower surfaces of the prepared aluminum-scandium target are sufficiently flat.

[0027] In some embodiments, the post-processing includes a cooling process and a cutting process in sequence.

[0028] In a specific embodiment, the cooling end temperature of the cooling step is room temperature.

[0029] In a specific embodiment, the cutting process includes turning and grinding.

[0030] In a specific embodiment, the cutting process is performed by using a CNC lathe and a grinder.

[0031] In the present invention, different ingots can be prepared by the following preferred method for preparing aluminum-scandium ingots to meet the needs in the production process.

[0032] In some embodiments, the method for preparing the aluminum-scandium ingot comprises the following steps: vacuum melting a mixture comprising aluminum particles and metal scandium; and then sequentially casting and cutting.

[0033] In a specific embodiment, the purity of the aluminum particles is above 99.999%, for example 99.999%.

[0034] In a specific embodiment, the aluminum particles are cylindrical, and the diameter D of the aluminum particles is 20 mm and the length L is 6 mm.

[0035] In a specific embodiment, the purity of the metallic scandium is 99.99%.

[0036] In a specific embodiment, the vacuum melting atmosphere includes argon; nitrogen should be filled into the system in advance before aluminum and metal scandium are intensively alloyed.

[0037] In a specific embodiment, the casting mold comprises a water-cooled mold.

[0038] In a specific embodiment, the cutting method includes horizontal cutting along a reference plane, and the reference plane includes a horizontal plane of the shrinkage cavity end of the aluminum-scandium ingot obtained by the casting step.

[0039] During the casting process, the aluminum-scandium ingot will naturally collapse and form a shrinkage cavity; the shrinkage cavity gradually decreases from top to bottom.

[0040] In some embodiments, the mold includes a plurality of orifices, each of which is arranged at the same height of the outer wall surface of the mold to provide space for inserting the transport part during transportation; the depth of the orifice is less than the difference between the outer diameter and the inner diameter of the mold.

[0041] In the present invention, other types of aluminum-scandium targets can be prepared by the scheme of this application. Due to the differences in internal phase composition and porosity of these aluminum-scandium targets, it is necessary to adjust the hot pressing process, such as temperature and pressure, based on this application.

[0042] The present invention provides an aluminum-scandium target material, which is prepared by the above-mentioned preparation method of the aluminum-scandium target material.

[0043] In some embodiments, in the aluminum-scandium target, the content ratio of aluminum to scandium is (90-70): (10-30).

[0044] In some embodiments, the aluminum-scandium target is further processed by sputtering the aluminum-scandium target in a nitrogen atmosphere to obtain a ScAlN target; wherein the upper limit of the doping amount of the scandium in the AlN is 43 at.%, where at.% is the ratio of the atomic weight of the scandium to the atomic weight of the aluminum-scandium target. When the doping amount of the scandium in the AlSc is 43 at.%, ScAlN exhibits the maximum piezoelectric response.

[0045] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0046] The reagents and raw materials used in the present invention are commercially available.

[0047] The positive and progressive effects of the present invention are:

[0048] 1. The present invention uses ingots as raw materials and a high-vacuum hot pressing process, which greatly shortens the target material preparation process, saves costs, reduces the introduction of impurities, and improves the relative density of the target material, which promotes the development of coating technology for downstream ScAlN products and the development of global integrated circuits and other fields.

[0049] 2. The present invention controls the distance between the mold and the aluminum-scandium ingot and maintains an ultra-high vacuum degree to avoid the presence of impurity gases and the like that may affect the quality of the target material. At the same time, the heat preservation and pressure holding time is controlled to make the target material densification process more complete.

[0050] 3. Compared with the traditional vacuum melting and direct casting of aluminum-scandium targets and powder metallurgy to manufacture aluminum-scandium targets, the present invention adopts the aluminum-scandium ingot to prepare aluminum-scandium targets under high vacuum hot pressing conditions, which can not only greatly reduce the internal defects and porosity of the casting alloy, but also avoid the problem of difficult control of target oxygen content and purity caused by the powder metallurgy process. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a comparison photo of the material appearance before and after the hot pressing and heat preservation treatment in Example 1 of the present application; wherein, Figure 1 Part a is the appearance of the aluminum-scandium ingot before hot pressing and heat preservation treatment. Figure 1 Part b is the appearance of the aluminum-scandium target after hot pressing and insulation treatment.

[0052] Figure 2 This is a comparison photo of the material appearance before and after the hot pressing and heat preservation treatment of Example 2 of the present application; wherein, Figure 2 Part a is the appearance of the aluminum-scandium ingot before hot pressing and heat preservation treatment. Figure 2 Part b is the appearance of the aluminum-scandium target after hot pressing and insulation treatment. DETAILED DESCRIPTION

[0053] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0054] Example 1

[0055] This embodiment discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0056] S1. Alloying high-purity aluminum particles and metal scandium in a vacuum melting furnace under an argon atmosphere to form a molten alloy; wherein the diameter D of the aluminum particles is 20 mm, the length L is 6 mm, and the purity of the aluminum particles is 99.99%; the diameter of the metal scandium is 20 mm, the length L is 30 mm, and the purity of the metal scandium is not less than 99.99%;

[0057] The obtained molten alloy is rapidly cast into an aluminum-scandium alloy, and the scandium content is maintained at 10at.%, where at.% represents the ratio of the scandium atom to the atomic weight of the aluminum-scandium target. During the casting process, a shrinkage cavity is naturally formed in the center of the aluminum-scandium alloy. The aluminum-scandium alloy with the shrinkage cavity is horizontally turned along the horizontal plane of the top of the shrinkage cavity to form an aluminum-scandium ingot with a diameter of 105.9mm and a thickness of 15mm to match a steel hot pressing mold with a diameter of 107.2mm (4 inches). The distance between the side of the cylindrical aluminum-scandium ingot and the inner wall of the mold of the internal cylindrical cavity is 0.65mm.

[0058] S2. Place the aluminum-scandium ingot obtained above in a 4-inch hot pressing mold, set steel blocks on the top and bottom, set a hot pressing head, and put it into a vacuum hot pressing furnace. Set the vacuum degree in the vacuum hot pressing furnace to 10 -3 Pa.

[0059] The temperature inside the vacuum hot pressing furnace is raised to 250°C within 30 minutes and kept warm for 20 minutes; then the temperature inside the furnace is raised to 610°C within 50 minutes for hot pressing and heat preservation treatment. The hot pressing and heat preservation treatment time is 6 hours. At this time, the pressure of the hot pressing and heat preservation treatment is set at 30Mpa±0.5Mpa. The pressure needs to be continuously adjusted during the process to maintain it within this range.

[0060] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50° C. in the furnace and taken out through demoulding. Finally, the 10at.% aluminum-scandium alloy is ground into a dense aluminum-scandium target material through a CNC lathe and a grinder.

[0061] Figure 1 This is a comparison photo of the material appearance before and after the hot pressing and heat preservation treatment in Example 1 of the present application; wherein, Figure 1 Part a is the appearance of the aluminum-scandium ingot before hot pressing and heat preservation treatment. Figure 1 Part b is the appearance of the aluminum-scandium target after hot pressing and heat preservation treatment. From the appearance, the 90at.%Al-10at.%Sc aluminum-scandium target after melting, casting and hot pressing in the embodiment has significantly less surface looseness and holes.

[0062] Example 2

[0063] This embodiment discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0064] S1. Alloying high-purity aluminum particles and metal scandium in a vacuum melting furnace under an argon atmosphere to form a molten alloy; wherein the diameter D of the aluminum particles is 20 mm, the length L is 6 mm, and the purity of the aluminum particles is 99.99%; the diameter of the metal scandium is 20 mm, the length L is 30 mm, and the purity of the metal scandium is not less than 99.99%;

[0065] The obtained molten alloy is rapidly cast into an aluminum-scandium alloy, and the scandium content is maintained at 20at.%, where at.% represents the ratio of the scandium atom to the atomic weight of the aluminum-scandium target. During the casting process, a shrinkage cavity is naturally formed in the center of the aluminum-scandium alloy. The aluminum-scandium alloy with the shrinkage cavity is horizontally turned along the horizontal plane of the top of the shrinkage cavity to form an aluminum-scandium ingot with a diameter of 105.9mm and a thickness of 15mm to match a steel hot pressing mold with a diameter of 107.2mm (4 inches). The distance between the side of the cylindrical aluminum-scandium ingot and the inner wall of the mold of the internal cylindrical cavity is 0.65mm.

[0066] S2. Place the aluminum-scandium ingot obtained above in a 4-inch hot pressing mold, set steel blocks on the top and bottom, set a hot pressing head, and put it into a vacuum hot pressing furnace. Set the vacuum degree in the vacuum hot pressing furnace to 10 -3 Pa.

[0067] The temperature inside the vacuum hot pressing furnace is raised to 250°C within 20 minutes and kept warm for 20 minutes; then the temperature inside the furnace is raised to 620°C within 50 minutes for hot pressing and heat preservation treatment. The hot pressing and heat preservation treatment time is 6 hours. At this time, the pressure of the hot pressing and heat preservation treatment is set at 30Mpa±0.5Mpa, and the pressure needs to be continuously adjusted during the process to maintain it within this range.

[0068] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50° C. in the furnace and taken out through demoulding. Finally, the 20at.% aluminum-scandium alloy is ground into a dense aluminum-scandium target material through a CNC lathe and a grinder.

[0069] Figure 2 The following are comparison photos of the material appearance before and after the hot pressing and heat preservation treatment in this embodiment; Figure 2 Part a is the appearance of the aluminum-scandium ingot before hot pressing and heat preservation treatment. Figure 2 Part b is the appearance of the aluminum-scandium target after hot pressing and heat preservation treatment. From the appearance, the 80at.%Al-20at.%Sc aluminum-scandium target after melting, casting and hot pressing in the embodiment has significantly less surface looseness and holes.

[0070] Example 3

[0071] This embodiment discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0072] S1. Alloying high-purity aluminum particles and metal scandium in a vacuum melting furnace under an argon atmosphere to form a molten alloy; wherein the diameter D of the aluminum particles is 20 mm, the length L is 6 mm, and the purity of the aluminum particles is 99.99%; the diameter of the metal scandium is 20 mm, the length L is 30 mm, and the purity of the metal scandium is not less than 99.99%;

[0073] The obtained molten alloy is rapidly cast into an aluminum-scandium alloy, and the scandium content is maintained at 30at.%, where at.% represents the ratio of the scandium atom to the atomic weight of the aluminum-scandium target. During the casting process, a shrinkage cavity is naturally formed in the center of the aluminum-scandium alloy. The aluminum-scandium alloy with the shrinkage cavity is horizontally turned along the horizontal plane of the top of the shrinkage cavity to form an aluminum-scandium ingot with a diameter of 157.2mm and a thickness of 15mm to match a hot pressing mold with a diameter of 158mm (6inch). The distance between the side of the cylindrical aluminum-scandium ingot and the inner wall of the mold of the internal cylindrical cavity is 0.4mm.

[0074] S2. Place the aluminum-scandium ingot obtained above in a 6-inch graphite mold, set a hot pressing head, and put it into a vacuum hot pressing furnace. Set the vacuum degree in the vacuum hot pressing furnace to 10 -3 Pa.

[0075] The temperature inside the vacuum hot pressing furnace is raised to 1150°C for hot pressing and heat preservation treatment. The time for hot pressing and heat preservation treatment is 6 hours. At this time, the pressure of hot pressing and heat preservation treatment is set at 60Mpa±0.5Mpa. The pressure needs to be continuously adjusted during the process to maintain it within this range.

[0076] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50°C in the furnace and taken out by demolding. Finally, the 30at.% aluminum-scandium alloy is ground by CNC lathe, grinder and multi-wire EDM to form a dense aluminum-scandium target.

[0077] Comparative Example 1

[0078] This comparative example discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0079] S1. A 10at.% aluminum-scandium ingot is prepared by a gas atomization method to obtain a 10at.% aluminum-scandium alloy powder. The specific process of the gas atomization method is as follows: the aluminum-scandium ingot is melted under gas protection conditions in a vacuum state, and the metal liquid falls downward through a heat-insulating crucible and a guide nozzle, and the metal liquid is atomized and broken into a large number of fine droplets by a high-pressure airflow through a nozzle, and the fine droplets solidify into spherical and sub-spherical particles in flight.

[0080] S2. Pour the aluminum-scandium alloy powder obtained above into a graphite hot pressing mold with a diameter of 158 mm (6 inches), set a hot pressing head, and put it into a vacuum hot pressing furnace. Set the vacuum degree in the vacuum hot pressing furnace to 10 -3 Pa.

[0081] The temperature inside the vacuum hot pressing furnace is raised to 610°C for hot pressing and heat preservation treatment. The time for hot pressing and heat preservation treatment is 6 hours. At this time, the pressure of hot pressing and heat preservation treatment is set at 60Mpa±0.5Mpa. The pressure needs to be continuously adjusted during the process to maintain it within this range.

[0082] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50° C. in the furnace and taken out by demolding. Finally, the 10at.% aluminum-scandium alloy is ground by a CNC lathe and a grinder to obtain an aluminum-scandium target.

[0083] Comparative Example 2

[0084] This comparative example discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0085] S1, preparing 30at.% aluminum-scandium alloy powder by gas atomization method from 30at.% aluminum-scandium ingot;

[0086] S2. Pour the aluminum-scandium alloy powder obtained above into a graphite hot pressing mold with a diameter of 158 mm (6 inches), set a hot pressing head, and put it into a vacuum hot pressing furnace. Set the vacuum degree in the vacuum hot pressing furnace to 10 -3 Pa.

[0087] The temperature inside the vacuum hot pressing furnace is raised to 1150°C for hot pressing and heat preservation treatment. The time for hot pressing and heat preservation treatment is 6 hours. At this time, the pressure of hot pressing and heat preservation treatment is set at 60Mpa±0.5Mpa. The pressure needs to be continuously adjusted during the process to maintain it within this range.

[0088] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50°C in the furnace and taken out by demolding. Finally, the 30at.% aluminum-scandium alloy is ground by CNC lathe, grinder and multi-wire electric spark cutting to obtain an aluminum-scandium target.

[0089] Effect Example 1

[0090] The Sc content in the aluminum-scandium target was tested by inductively coupled plasma (ICP) on Examples 1-3 and Comparative Examples 1-2, wherein the ICP used a test instrument model ICP-MS2000 produced by Skyray Instruments. Secondly, the oxygen content in the aluminum-scandium target was measured by infrared gas analysis, wherein the infrared gas analysis used a test instrument model RL-S100H produced by Runlai Instruments. In addition, the relative density of the aluminum-scandium target was measured by the Archimedean drainage method.

[0091] The results of Examples 1-3 and Comparative Examples 1-2 were compared, as shown in Table 1. Table 1 is the target material test results.

[0092] Table 1

[0093]

[0094] It can be seen from Table 1 that the oxygen content values ​​given in Examples 1-3 of the present invention are all below 200 ppm, and the relative density is above 98.5%. The greater the pressure during the hot pressing process, the lower the oxygen content and the higher the relative density.

[0095] Comparative Example 3

[0096] This comparative example discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0097] S1. Alloying high-purity aluminum particles and metal scandium in a vacuum melting furnace under an argon atmosphere to form a molten alloy; wherein the diameter D of the aluminum particles is 20 mm, the length L is 6 mm, and the purity of the aluminum particles is 99.99%; the diameter of the metal scandium is 20 mm, the length L is 30 mm, and the purity of the metal scandium is not less than 99.99%;

[0098] The obtained molten alloy is quickly cast into an aluminum-scandium alloy, and the scandium content is maintained at 10at.%, where at.% represents the ratio of the scandium atom to the atomic weight of the aluminum-scandium target. The aluminum-scandium alloy is processed into a block aluminum-scandium alloy of 30mm*20mm size, and powdered by gas atomization, with a sieve mesh of 200.

[0099] S2, putting the powder obtained above into a hot pressing graphite female mold and pre-pressing to remove air, slowly evacuating the mold and then starting heating;

[0100] The temperature inside the vacuum hot pressing furnace is raised to 250°C within 30 minutes and kept warm for 20 minutes; then the temperature inside the furnace is raised to 580°C within 50 minutes for hot pressing and heat preservation treatment. The hot pressing and heat preservation treatment time is 6 hours. At this time, the pressure of the hot pressing and heat preservation treatment is set at 25Mpa±0.5Mpa, and the pressure needs to be continuously adjusted during the process to maintain it within this range.

[0101] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50° C. in the furnace and taken out by demolding. Finally, the 10at.% aluminum-scandium alloy is ground by a CNC lathe and a grinder to obtain an aluminum-scandium target.

[0102] The Archimedes drainage method and infrared gas analysis measurement method in Example 1 were used to measure the density and oxygen content respectively, and the relative density and oxygen content of the comparative target block were found to be 92% and 450 ppm respectively.

[0103] Comparative Example 4

[0104] This comparative example discloses an aluminum-scandium target material and a preparation method thereof. The preparation method of the aluminum-scandium target material comprises the following steps:

[0105] S1. Alloying high-purity aluminum particles and metal scandium in a vacuum melting furnace under an argon atmosphere to form a molten alloy; wherein the diameter D of the aluminum particles is 20 mm, the length L is 6 mm, and the purity of the aluminum particles is 99.99%; the diameter of the metal scandium is 20 mm, the length L is 30 mm, and the purity of the metal scandium is not less than 99.99%;

[0106] The obtained molten alloy is rapidly cast into an aluminum-scandium alloy, and the scandium content is maintained at 10at.%, where at.% represents the ratio of the scandium atom to the atomic weight of the aluminum-scandium target. During the casting process, a shrinkage cavity is naturally formed in the center of the aluminum-scandium alloy. The aluminum-scandium alloy with the shrinkage cavity is horizontally turned along the horizontal plane of the top of the shrinkage cavity to form an aluminum-scandium ingot with a diameter of 157.2 mm and a thickness of 15 mm to match a hot pressing mold with a diameter of 158 mm (6 inches). The distance between the side of the cylindrical aluminum-scandium ingot and the inner wall of the mold of the internal cylindrical cavity is 0.4 mm.

[0107] S2. Place the aluminum-scandium ingot obtained above in a 6-inch graphite mold, set a hot pressing head, and put it into a vacuum hot pressing furnace, and set the vacuum degree in the vacuum hot pressing furnace to 1 Pa.

[0108] The temperature inside the vacuum hot pressing furnace is raised to 450°C for hot pressing and heat preservation treatment. The time for hot pressing and heat preservation treatment is 6 hours. At this time, the pressure of hot pressing and heat preservation treatment is set at 30Mpa±0.5Mpa. The pressure needs to be continuously adjusted during the process to maintain it within this range.

[0109] S3. After the hot pressing and heat preservation treatment is completed, the aluminum-scandium alloy is cooled to below 50°C in the furnace and taken out by demolding. Finally, the 10at.% aluminum-scandium alloy is ground by CNC lathe, grinder and multi-wire EDM to form a dense aluminum-scandium target.

[0110] The Archimedes drainage method and infrared gas analysis measurement method in Example 1 were used to measure the density and oxygen content respectively, and the relative density and oxygen content of the comparative target block were obtained to be 88% and 550 ppm respectively.

Claims

1. A method for preparing an aluminum-scandium target, characterized in that: It includes the following steps: The mold containing the aluminum-scandium ingot is placed in a vacuum of 10 -3 ~10 -2 Pa, and then undergo post-treatment to obtain an aluminum-scandium target; wherein the pressure of the hot pressing and heat preservation treatment is 25-60 MPa; the temperature of the hot pressing and heat preservation treatment is 610-1200°C; and the time of the hot pressing and heat preservation treatment is 2-10 h; The distance between the side surface of the aluminum-scandium ingot and the inner wall surface of the mold is less than or equal to 1 mm.

2. The method for preparing an aluminum-scandium target according to claim 1, characterized in that: The method for preparing the aluminum-scandium target meets one or more of the following conditions: ① The hot pressing and heat preservation treatment is carried out in a vacuum melting furnace; ② The temperature of the hot pressing and heat preservation treatment is 610-800°C; ③ The hot pressing and heat preservation treatment also includes a gradient heating step; the gradient heating step includes a first-stage heating and a second-stage heating.

3. The method for preparing an aluminum-scandium target according to claim 2, characterized in that: The method for preparing the aluminum-scandium target meets one or more of the following conditions: ① The pressure of the hot pressing and heat preservation treatment is 30-40 MPa; ② Control the pressure of the hot pressing and heat preservation treatment to float within the range of ±0.5Mpa; ③ The temperature of the hot pressing and heat preservation treatment is 630-800°C; ④ The time of the hot pressing and heat preservation treatment is 2 to 6 hours.

4. The method for preparing an aluminum-scandium target according to claim 1, characterized in that: The mold contains a cavity, and the shape of the cavity is the same as the shape of the aluminum-scandium ingot; on any cross section, the difference between the radius of the aluminum-scandium ingot and the radius of the inner wall surface of the mold is less than or equal to 1 mm.

5. The method for preparing an aluminum-scandium target according to claim 1, characterized in that: The post-processing includes a cooling process and a cutting process in sequence; The cooling process or the cutting process satisfies one or more of the following conditions: ① The cooling end temperature of the cooling process is room temperature; ② The cutting process includes turning and grinding; ③The cutting process is carried out by using a CNC lathe and a grinder.

6. The method for preparing an aluminum-scandium target according to claim 1, characterized in that: The method for preparing the aluminum-scandium ingot comprises the following steps: vacuum melting a mixture, the mixture comprising aluminum particles and metal scandium; then casting and cutting in sequence; wherein the aluminum particles or the metal scandium meet one or more of the following conditions: ① The purity of the aluminum particles is above 99.999%; ② The aluminum particles are cylindrical, with a diameter D of 20 mm and a length L of 6 mm; ③ The purity of the metal scandium is 99.99%.

7. The method for preparing an aluminum-scandium target according to claim 6, characterized in that: The method for preparing the aluminum-scandium ingot satisfies one or more of the following conditions: ① The vacuum melting atmosphere includes argon; ② The casting mold includes a water-cooled mold; ③ The cutting method includes horizontal cutting along a reference plane, and the reference plane includes the horizontal plane of the top of the shrinkage cavity of the aluminum-scandium ingot obtained by the casting step.

8. The method for preparing an aluminum-scandium target according to claim 6, characterized in that: The mold includes a plurality of openings, each of which is arranged at the same height of the outer wall surface of the mold to provide space for inserting the transported parts during transportation; the depth of the opening is less than the difference between the outer diameter and the inner diameter of the mold.

9. An aluminum-scandium target, characterized in that: The target is prepared by the method for preparing the aluminum-scandium target as described in any one of claims 1 to 8.

10. The aluminum-scandium target material according to claim 9, characterized in that: In the aluminum-scandium target material, the content ratio of aluminum to scandium is (90-70):(10-30).

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