A method for manufacturing a heavy rare earth foil

Abstract

The application provides a preparation method of heavy rare earth foil, comprising the following steps: firstly, annealing a heavy rare earth ingot to obtain a rolling blank; then, coating the rolling blank obtained in the above step with copper to obtain a copper-coated rolling blank, subsequently, adopting an asynchronous rolling process to perform multi-pass hot rolling, then, performing recrystallization annealing, and then, performing medium-temperature rolling to obtain the heavy rare earth foil. The application adopts a multi-heat treatment and multi-pass rolling cooperation method, simultaneously combines the sleeve rolling and asynchronous rolling method, accurately controls process temperature, deformation and other parameters, and thus obtains a specific preparation method of the heavy rare earth foil. The application can prepare the foil with high relative purity, small grain, high surface smoothness, high size precision and good use performance, has the advantages of low waste rate and short production cycle, and has the advantages of simple process, good stability, high on-site executability, and is more suitable for popularization and application of industrialized scale production.

Description

Technical Field

[0001] This invention belongs to the field of heavy rare earth foil preparation technology, and relates to a method for preparing heavy rare earth foil. Background Technology

[0002] Sputtering targets, also known as sputtering targets, refer to the materials sputtered during the sputtering deposition process. Sputtering is a material deposition method that uses accelerated charged particles (ions) to bombard the surface of a target, "stripping" atoms or molecules from the target surface and then depositing them onto a substrate to form a thin film. With the increasingly widespread application of rare earth elements in various fields, the demand for rare earth targets is also rising.

[0003] In existing rare earth target preparation processes, heavy rare earth metal billets of a certain thickness are usually obtained by vacuum melting, and then thinner sheets or foils are prepared by multi-wire cutting. However, this process has high machining losses and low yield. Moreover, for heavy rare earth metals, hot rolling is prone to oxidation and cold rolling is prone to cracking, which also has the characteristics of low yield.

[0004] Therefore, finding a more suitable way to prepare heavy rare earth foils and solving the above-mentioned defects in the existing heavy rare earth foil preparation process has become one of the urgent problems to be solved by many front-line researchers and forward-looking R&D companies in the industry. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing heavy rare earth foil. The preparation method provided by the present invention can obtain heavy rare earth foil with relatively high purity, fine grains, high surface smoothness, high dimensional accuracy, and good performance, and has the advantages of low scrap rate and short production cycle. Moreover, the preparation process is simple, stable, highly controllable, and highly executable on site, making it more suitable for promotion and application in industrial-scale production.

[0006] This invention provides a method for preparing heavy rare earth foil, comprising the following steps:

[0007] 1) After annealing, heavy rare earth ingots are used to obtain rolled blanks;

[0008] 2) After the rolled blank obtained in the above steps is coated with copper, a copper-clad rolled blank is obtained. Then, an asynchronous rolling process is used for multiple hot rolling passes. After recrystallization annealing, it is rolled at medium temperature to obtain heavy rare earth foil.

[0009] The heavy rare earth elements include Dy, Gd, Tb, Ho, or Er.

[0010] Preferably, the purity of the heavy rare earth ingot is 99% to 99.995%;

[0011] The annealing method includes annealing under vacuum conditions;

[0012] The annealing temperature is 600–1000℃;

[0013] The annealing time is 1 to 4 hours.

[0014] Preferably, the rolled blank of the copper cladding is specifically formed by coating the surface of the rolled blank with a copper cladding layer;

[0015] The thickness of the copper cladding layer is 0.5–2.5 mm;

[0016] The rolling speed of the upper roll in the asynchronous rolling process is 0–45 m / min;

[0017] The rolling speed of the lower roll in the asynchronous rolling process is 1 to 65 m / min;

[0018] The ratio of the lower roll speed to the upper roll speed in the asynchronous rolling process is 1.12 to 1.65.

[0019] Preferably, the number of hot rolling passes is 9 to 14.

[0020] The multi-pass hot rolling includes multi-pass hot rolling at a first temperature and multi-pass hot rolling at a second temperature.

[0021] Preferably, the first temperature is 600–900°C;

[0022] The number of passes in the multi-pass hot rolling at the first temperature is 4 to 6.

[0023] The reduction rate per pass in the multi-pass hot rolling at the first temperature is 5% to 10%.

[0024] Preferably, the second temperature is 450–750°C;

[0025] The number of passes in the multi-pass hot rolling at the second temperature is 5 to 8.

[0026] The reduction rate per pass in the multi-pass hot rolling at the second temperature is 7% to 15%.

[0027] Preferably, the recrystallization annealing method includes annealing under vacuum conditions;

[0028] The recrystallization annealing temperature is 500–800°C;

[0029] The recrystallization annealing time is 1 to 3 hours.

[0030] Preferably, the medium-temperature rolling method includes performing multi-pass medium-temperature rolling on the copper cladding blank using an asynchronous rolling process;

[0031] The medium-temperature rolling process involves 15 to 30 passes.

[0032] Preferably, the temperature of the medium-temperature rolling is 200–500°C;

[0033] During the medium-temperature rolling process, the reduction rate is adjusted every 3 to 5 passes.

[0034] The reduction rate per pass in the medium-temperature rolling process is 3% to 8%.

[0035] Preferably, the thickness of the heavy rare earth foil is 0.1 to 1 mm;

[0036] The grain size of the heavy rare earth foil is 10–50 μm;

[0037] The purity of the heavy rare earth foil is 99% to 99.995%.

[0038] This invention provides a method for preparing heavy rare earth foil, comprising the following steps: first, heavy rare earth ingots are annealed to obtain rolled blanks; then, the rolled blanks obtained in the above steps are clad with copper to obtain copper-clad rolled blanks; subsequently, asynchronous rolling is used for multi-pass hot rolling; after recrystallization annealing, medium-temperature rolling is performed to obtain heavy rare earth foil. Compared with the prior art, this invention creatively designs and optimizes the rolling process, employing a combination of various heat treatments and multi-pass rolling methods, while combining cladding rolling and asynchronous rolling. By precisely controlling parameters such as process temperature and deformation, a specific method for preparing heavy rare earth foil is obtained. The preparation method provided by this invention can obtain heavy rare earth foils with relatively high purity, fine grains, high surface smoothness, high dimensional accuracy, and good performance. It has the advantages of low scrap rate and short production cycle. Moreover, the preparation process is simple, stable, highly controllable, and highly executable on-site, making it more suitable for industrial-scale production and application.

[0039] The preparation method provided by this invention particularly combines and applies cladding rolling, asynchronous rolling, vacuum heat treatment, and precise control of rolling process parameters. The cladding rolling process reduces friction and improves temperature uniformity; the interspersed asynchronous rolling process ensures a flat slab shape and avoids warping that could affect the uniformity of rolling stress; precise control of the heat treatment sequence and temperature eliminates slab cracks; precise control of the rolling temperature, employing gradient temperature rolling, prevents severe oxidation during the rolling process; precise control of the deformation amount in each pass reduces the tendency for surface cracking during rolling; and the rational combination of heat treatment and rolling processes achieves a relatively optimized grain refinement effect. Attached Figure Description

[0040] Figure 1 Photographs showing the physical appearance of the heavy rare earth Dy foil material prepared according to the present invention;

[0041] Figure 2 Metallographic image of the metal Dy foil prepared in Example 1 of this invention;

[0042] Figure 3 Metallographic image of the metal Dy foil prepared in Example 2 of this invention;

[0043] Figure 4 This is a metallographic image of the metal Dy foil prepared in Example 3 of the present invention. Detailed Implementation

[0044] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.

[0045] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0046] There are no particular restrictions on the purity of any of the raw materials used in this invention. However, this invention preferably adopts analytical grade or the purity requirements conventional in the field of heavy rare earth foil preparation.

[0047] All raw materials of this invention are conventional in the field, and each brand name and abbreviation is clear and distinct in its relevant application. Those skilled in the art can purchase them from the market or prepare them by conventional methods based on the brand name, abbreviation and corresponding application.

[0048] The processes used in this invention are all commonly referred to in the field. The specific steps and conventional parameters of each abbreviation are clear and well-defined in their respective fields. Those skilled in the art can implement them using conventional methods based on the abbreviations.

[0049] This invention provides a method for preparing heavy rare earth foil, comprising the following steps:

[0050] 1) After annealing, heavy rare earth ingots are used to obtain rolled blanks;

[0051] 2) After the rolled blank obtained in the above steps is coated with copper, a copper-clad rolled blank is obtained. Then, an asynchronous rolling process is used for multiple hot rolling passes. After recrystallization annealing, it is rolled at medium temperature to obtain heavy rare earth foil.

[0052] The heavy rare earth elements include Dy, Gd, Tb, Ho, or Er. Specifically, it can be Dy.

[0053] The present invention first anneals heavy rare earth ingots to obtain rolled blanks.

[0054] In this invention, the heavy rare earth ingot can be a square ingot. After machining (surface polishing), it can be directly annealed and rolled without extrusion. This avoids problems such as peeling after extrusion, large losses, and low yield.

[0055] In this invention, the purity of the heavy rare earth ingot is preferably 99% to 99.995%, can be 99.9% to 99.993%, and more preferably 99.95% to 99.991%.

[0056] In this invention, the annealing method preferably includes annealing under vacuum conditions.

[0057] In this invention, the annealing temperature is preferably 600-1000℃, more preferably 650-950℃, more preferably 700-900℃, and even more preferably 750-850℃.

[0058] In this invention, the annealing time is preferably 1 to 4 hours, more preferably 1.5 to 3.5 hours, and even more preferably 2 to 3 hours.

[0059] The present invention involves coating the rolled blank obtained in the above steps with copper to obtain a copper-clad rolled blank, then performing multi-pass hot rolling using an asynchronous rolling process, followed by recrystallization annealing and then medium-temperature rolling to obtain heavy rare earth foil.

[0060] In this invention, the copper cladding is preferably formed by coating the surface of the rolled blank with a copper cladding layer. Specifically, the copper cladding in this invention involves coating the material blank with copper, and the copper cladding will not be damaged during the rolling process.

[0061] In this invention, the thickness of the copper cladding layer is preferably 0.5 to 2.5 mm, more preferably 1.0 to 1.5 mm.

[0062] In this invention, the rolling speed of the upper roll in the asynchronous rolling is preferably 0 to 45 m / min, more preferably 10 to 35 m / min, and even more preferably 20 to 25 m / min.

[0063] In this invention, the rolling speed of the lower roll in the asynchronous rolling is preferably 1 to 65 m / min, more preferably 10 to 55 m / min, more preferably 20 to 45 m / min, and even more preferably 30 to 35 m / min.

[0064] In this invention, the speed ratio of the lower roll speed to the upper roll speed in the asynchronous rolling is preferably 1.12 to 1.65, more preferably 1.22 to 1.55, and even more preferably 1.32 to 1.45. Specifically, the rolling speed of the lower roll in the asynchronous rolling is preferably greater than the rolling speed of the upper roll.

[0065] In this invention, the number of hot rolling passes is preferably 9 to 14, more preferably 10 to 13, and even more preferably 11 to 12.

[0066] In this invention, the multi-pass hot rolling preferably includes multi-pass hot rolling at a first temperature and multi-pass hot rolling at a second temperature.

[0067] In this invention, the first temperature is preferably 600-900°C, more preferably 650-850°C, and even more preferably 700-800°C.

[0068] In this invention, the number of passes in the multi-pass hot rolling at the first temperature is preferably 4 to 6.

[0069] In this invention, the reduction rate per pass of the multi-pass hot rolling at the first temperature is preferably 5% to 10%, more preferably 6% to 9%, and even more preferably 7% to 8%.

[0070] In this invention, the second temperature is preferably 450-750°C, more preferably 500-700°C, and even more preferably 650-650°C.

[0071] In this invention, the number of passes in the multi-pass hot rolling at the second temperature is preferably 5 to 8, more preferably 6 to 7.

[0072] In this invention, the reduction rate per pass of the multi-pass hot rolling at the second temperature is preferably 7% to 15%, more preferably 8% to 14%, more preferably 9% to 13%, and even more preferably 10% to 12%.

[0073] In this invention, the recrystallization annealing method preferably includes annealing under vacuum conditions.

[0074] In this invention, the recrystallization annealing temperature is preferably 500-800°C, more preferably 550-750°C, and even more preferably 600-700°C.

[0075] In this invention, the recrystallization annealing time is preferably 1 to 3 hours, more preferably 1.2 to 2.8 hours, and even more preferably 1.5 to 2.5 hours.

[0076] In this invention, the medium-temperature rolling method preferably includes using an asynchronous rolling process to perform multi-pass medium-temperature rolling on the copper cladding blank.

[0077] In this invention, the number of passes in the medium-temperature rolling is preferably 15 to 30, more preferably 18 to 27, and even more preferably 21 to 24.

[0078] In this invention, the temperature of the medium-temperature rolling is preferably 200℃~500℃, more preferably 250~450℃, and even more preferably 300~400℃.

[0079] In this invention, the medium-temperature rolling process preferably involves adjusting the reduction rate every 3 to 5 passes.

[0080] In this invention, the reduction rate per pass of the medium-temperature rolling is preferably 3% to 8%, more preferably 4% to 7%, and even more preferably 5% to 6%.

[0081] In this invention, the thickness of the heavy rare earth foil is preferably 0.1-1 mm, more preferably 0.3-0.8 mm, and even more preferably 0.5-0.6 mm.

[0082] In this invention, the grain size of the heavy rare earth foil is preferably 10-50 μm, more preferably 18-42 μm, and even more preferably 26-34 μm.

[0083] In this invention, the purity of the heavy rare earth foil is preferably 99% to 99.995%, more preferably 99.2% to 99.8%, and even more preferably 99.4% to 99.6%. Specifically, the purity value of the heavy rare earth remains stable and consistent before and after the preparation method of this invention, and the preparation method does not affect the purity of the heavy rare earth.

[0084] This invention provides a complete and refined overall technical solution to better improve the surface finish, dimensional accuracy, and performance of heavy rare earth foils, reduce the grain size and scrap rate of heavy rare earth foils, shorten the production cycle, and ensure the stability and controllability of the preparation process. The specific preparation method for the aforementioned heavy rare earth foils may include the following steps:

[0085] Pre-rolling full annealing is adopted to optimize the internal structure of the material and reduce its hardness; gradient cooling multi-pass rolling is used to reduce the degree of oxidation while ensuring a reduction in the tendency to crack; intermediate rolling passes are used to recrystallize and anneal the material to eliminate processing stress and refine the grains.

[0086] 1. The Dy ingot is fully annealed to obtain a rolled blank;

[0087] Specifically, the full annealing described in this invention is carried out under vacuum conditions, with an annealing temperature of 600℃~1000℃ and an annealing time of 1h~4h.

[0088] 2. The composite copper cladding rolling process is adopted. The copper cladding rolls the blank, so that the rolled blank does not directly contact the rolls, reducing friction and improving temperature uniformity.

[0089] 3. Asynchronous rolling process is used intermittently, with the upper roll rolling speed being 0-45 m / min and the lower roll rolling speed being 0-65 m / min, to ensure the flatness of the plate during the process and avoid warping that would affect the uniformity of rolling stress.

[0090] Specifically, the fully annealed blank is hot-rolled 4-6 times at a temperature of 600℃-900℃, with a reduction of 5%-10% per pass; then hot-rolled 5-8 times at a temperature of 450℃-750℃, with a reduction of 7%-15% per pass. After recrystallization annealing, it is rolled 15-30 times at a medium-temperature temperature of 200℃-500℃, with a reduction of 3%-8%, and the reduction is adjusted every 3-5 passes; finally, a heavy rare earth Dy foil with a thickness of 0.1mm-1mm is obtained.

[0091] Specifically, all of the above-mentioned annealing in this invention is carried out under vacuum conditions.

[0092] See Figure 1 , Figure 1 Photographs showing the physical appearance of the heavy rare earth Dy foil prepared according to the present invention.

[0093] This invention provides the application of the preparation method described in any one of the above technical solutions in the preparation of heavy rare earth foil materials for magnetron sputtering or grain boundary diffusion.

[0094] The present invention provides a method for preparing heavy rare earth foil. The invention designs and optimizes the rolling process, employing a combination of various heat treatments and multi-pass rolling, along with cladding rolling and asynchronous rolling. By precisely controlling parameters such as process temperature and deformation, a specific method for preparing heavy rare earth foil is obtained. The preparation method provided by the present invention can obtain heavy rare earth foil with relatively high purity, fine grains, high surface smoothness, high dimensional accuracy, and excellent performance. It has the advantages of low scrap rate and short production cycle. Moreover, the preparation process is simple, stable, highly controllable, and highly executable on-site, making it more suitable for promotion and application in industrial-scale production.

[0095] The preparation method provided by this invention particularly combines and applies cladding rolling, asynchronous rolling, vacuum heat treatment, and precise control of rolling process parameters. The cladding rolling process reduces friction and improves temperature uniformity; the interspersed asynchronous rolling process ensures a flat slab shape and avoids warping that could affect the uniformity of rolling stress; precise control of the heat treatment sequence and temperature eliminates slab cracks; precise control of the rolling temperature, employing gradient temperature rolling, prevents severe oxidation during the rolling process; precise control of the deformation amount in each pass reduces the tendency for surface cracking during rolling; and the rational combination of heat treatment and rolling processes achieves a relatively optimized grain refinement effect.

[0096] To further illustrate the present invention, the following describes in detail a method for preparing heavy rare earth foil provided by the present invention with reference to embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. They are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0097] Example 1

[0098] A rolled blank was obtained by annealing a heavy rare earth Dy ingot with a purity of 2N5 under vacuum conditions at 800℃ / 1h.

[0099] The rolled blank is clad with copper to a thickness of 2 mm to obtain a copper-clad rolled blank. Then, asynchronous rolling is performed (upper roll speed 20 m / min, lower roll speed 30 m / min, speed ratio 1.5). The fully annealed copper-clad rolled blank is then hot rolled in 4 passes at a temperature of 900℃, with a reduction of 10% per pass. Then, it is hot rolled in 5 passes, also using asynchronous rolling (upper roll speed 20 m / min, lower roll speed 30 m / min, speed ratio 1.5), at a temperature of 800℃, with a reduction of 15% per pass.

[0100] Then, recrystallization annealing was carried out under vacuum conditions at a temperature of 800℃ for 1 hour.

[0101] Finally, 15 passes of medium-temperature rolling are performed, also using asynchronous rolling (upper roll speed 25, lower roll speed 28, speed ratio 1.12), rolling temperature 350℃, reduction rate 8%, and the reduction is adjusted once every 4 passes to perform the downward pressing action.

[0102] The final product is a 1mm thick metal Dy foil.

[0103] The metal Dy foil prepared in Example 1 of the present invention was characterized and its performance was tested.

[0104] The test results show that the metal Dy foil prepared in Example 1 of this invention has a purity of 99.5%, a grain size of 48μm, good flatness, high smoothness, no defects such as pores or cracks, a length and width of ±1mm, a thickness of ±0.1mm, and a scrap rate of <2%.

[0105] See Figure 2 , Figure 2 This is a metallographic image of the metal Dy foil prepared in Example 1 of the present invention.

[0106] Example 2

[0107] A rolled blank was obtained by annealing a heavy rare earth Dy ingot with a purity of 3N under vacuum conditions at 750℃ for 1.5h.

[0108] The rolled blank is clad with copper to a thickness of 1.5 mm, resulting in a copper-clad rolled blank. It is then subjected to asynchronous rolling (upper roll speed 24 m / min, lower roll speed 30 m / min, speed ratio 1.25). The fully annealed copper-clad rolled blank is then hot rolled in 5 passes at 800℃, with a reduction of 8% per pass. Then, it is hot rolled in 7 passes, again using asynchronous rolling (upper roll speed 24 m / min, lower roll speed 30 m / min, speed ratio 1.25), at 700℃, with a reduction of 12% per pass.

[0109] Then, recrystallization annealing was carried out under vacuum conditions at a temperature of 650℃ and a time of 1.5h.

[0110] Finally, 20 passes of medium-temperature rolling are performed, also using asynchronous rolling (upper roll speed 25, lower roll speed 28, speed ratio 1.12), rolling temperature 320℃, reduction rate 6%, and the reduction is adjusted once every 3 passes to perform the downward pressing action.

[0111] The final product is a 0.7mm thick metal Dy foil.

[0112] The metal Dy foil prepared in Example 2 of the present invention was characterized and its performance was tested.

[0113] The test results show that the metal Dy foil prepared in Example 2 of this invention has a purity of 99.9%, a grain size of 35μm, good flatness, high smoothness, no defects such as pores or cracks, a length and width of ±1mm, a thickness of ±0.1mm, and a scrap rate of <3%.

[0114] See Figure 3 , Figure 3 This is a metallographic image of the metal Dy foil prepared in Example 2 of the present invention.

[0115] Example 3

[0116] A rolled billet was obtained by annealing a heavy rare earth Dy ingot with a purity of 3N5 under vacuum conditions at 700℃ for 2 hours.

[0117] The rolled blank is clad with copper with a cladding thickness of 1.0 mm to obtain a copper-clad rolled blank. Then, asynchronous rolling is performed (upper roll speed 20 m / min, lower roll speed 24 m / min, speed ratio 1.2). The fully annealed copper-clad rolled blank is then hot rolled in 6 passes at a temperature of 700℃, with a reduction of 6% per pass. Then, it is hot rolled in 8 passes, also using asynchronous rolling (upper roll speed 20 m / min, lower roll speed 24 m / min, speed ratio 1.2), at a rolling temperature of 600℃, with a reduction of 10% per pass.

[0118] Then, recrystallization annealing was carried out under vacuum conditions at a temperature of 550℃ for 2 hours.

[0119] Finally, 25 passes of medium-temperature rolling are performed, also using asynchronous rolling, with an upper roll speed of 25, a lower roll speed of 28, a speed ratio of 1.12, a rolling temperature of 280℃, and a reduction rate of 5%. The reduction is adjusted every 3 passes to perform the downward pressing action.

[0120] The final product is a 0.5mm thick metal Dy foil.

[0121] The metal Dy foil prepared in Example 3 of the present invention was characterized and its performance was tested.

[0122] The test results show that the metal Dy foil prepared in Example 3 of this invention has a purity of 99.95%, a grain size of 20μm, good flatness, high smoothness, no defects such as pores or cracks, a length and width of ±1mm, a thickness of ±0.1mm, and a scrap rate of <3%.

[0123] See Figure 4 , Figure 4 This is a metallographic image of the metal Dy foil prepared in Example 3 of the present invention.

[0124] The preparation method of heavy rare earth foil provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The scope of protection of the present invention is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the textual description of the claims, or if they include equivalent structural elements that are not substantially different from the textual description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for producing a heavy rare earth foil, characterized by, The method comprises the following steps: 1) obtaining a rolling blank after annealing a heavy rare earth ingot; 2) obtaining a copper-coated rolling blank after coating the rolling blank obtained in the above step with copper, then performing multi-pass hot rolling using an asynchronous rolling process, and then performing recrystallization annealing and then performing medium-temperature rolling to obtain a heavy rare earth foil; The heavy rare earth comprises Dy, Gd, Tb, Ho or Er; The number of the multi-pass hot rolling is 9-14; The multi-pass hot rolling comprises multi-pass hot rolling at a first temperature and multi-pass hot rolling at a second temperature; The first temperature is 600-900 DEG C; The number of the multi-pass hot rolling at the first temperature is 4-6; The reduction rate of each pass of the multi-pass hot rolling at the first temperature is 5-10%; The second temperature is 450-750 DEG C; The number of the multi-pass hot rolling at the second temperature is 5-8; The reduction rate of each pass of the multi-pass hot rolling at the second temperature is 7-15%; The medium-temperature rolling comprises multi-pass medium-temperature rolling of the copper-coated blank using an asynchronous rolling process; The number of the medium-temperature rolling is 15-30; The temperature of the medium-temperature rolling is 200-500 DEG C; The medium-temperature rolling adjusts the reduction rate once every 3-5 passes; The reduction rate of each pass of the medium-temperature rolling is 3-8%.

2. The production method according to claim 1, characterized by, The purity of the heavy rare earth ingot is 99-99.995%.

3. The preparation method according to claim 1, characterized in that, The annealing is performed under vacuum.

4. The production method according to claim 3, characterized by, The temperature of the annealing is 600-1000 DEG C; The time of the annealing is 1-4 h.

5. The preparation method according to claim 1, characterized in that, The copper-coated rolling blank is specifically a rolling blank coated with a copper coating layer on the surface of the rolling blank; The thickness of the copper coating layer is 0.5-2.5 mm.

6. The method of claim 1, wherein, The upper roller rolling speed of the asynchronous rolling is 0-45 m / min; The lower roller rolling speed of the asynchronous rolling is 1-65 m / min; The asynchronous ratio of the lower roller speed to the upper roller speed of the asynchronous rolling is 1.12-1.

65.

7. The preparation method according to claim 1, characterized in that, The recrystallization annealing is performed under vacuum.

8. The method of claim 1, wherein, The temperature of the recrystallization annealing is 500-800 DEG C; The time of the recrystallization annealing is 1-3 h.

9. The method of claim 1, wherein, The thickness of the heavy rare earth foil is 0.1-1 mm.

10. The method of claim 1, wherein, The grain size of the heavy rare earth foil is 10-50 mu m; The purity of the heavy rare earth foil is 99-99.995%.

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