Low reaction threshold rare earth modified medium entropy alloy and preparation method thereof

Abstract

The application discloses a low reaction threshold value rare earth modified medium entropy alloy, characterized in that the low reaction threshold value rare earth modified medium entropy alloy is a TiZrTa medium entropy alloy, and an element Ce is used as the rare earth.The application further discloses a preparation method of the rare earth modified medium entropy alloy.The vacuum sintering and the vacuum high-frequency induction melting are used, and the obtained alloy has high strength, good plasticity, excellent energy release characteristics and a low reaction threshold value, and has potential application value in an energetic structure material.

Description

TECHNICAL FIELD

[0001] The present application relates to a TiZrTa medium-entropy alloy, and the TiZrTa medium-entropy alloy is applied to a high-efficiency damage weapon. BACKGROUND

[0002] Energetic structural material is a new type of structural and functional integrated material for future high-efficiency damage weapons. The energetic structural material has high structural stability in a conventional state, and reaches a plastic deformation limit and is broken into small metal damage elements under the action of a high-speed impact load. In addition to the kinetic energy penetration effect, the metal damage elements can also have a self-reaction between components or an oxidation reaction between components and the environment, release a large amount of chemical energy, and produce strong combustion or even a quasi-detonation phenomenon, so as to achieve an ideal damage mode of mechanical damage and chemical damage coupling.

[0003] The entropy-controlled alloy represented by the medium-entropy alloy has high energy density, high strength, and good plastic deformation capacity, and has potential application value in the field of energetic structural materials. However, the excellent strength and toughness also restrict the breaking behavior of the medium-entropy alloy under high-speed impact, resulting in a high reaction threshold of the medium-entropy alloy. According to existing data, the speed threshold for the medium-entropy alloy to release significant energy is usually above 1200 m / s, and the terminal speed of the current fragment damage element is usually less than 1000 m / s, which is difficult to fully stimulate the energy release reaction of the medium-entropy alloy. In addition, the energy release rate of the medium-entropy alloy under high-speed impact is generally less than 15%, and a large amount of chemical energy is wasted.

[0004] Rare earth elements have active chemical properties, low ignition temperature, and long burning time, and are widely used as combustion materials. How to use rare earth elements to improve the performance of medium-entropy alloys has been a research hotspot. SUMMARY

[0005] The first technical problem to be solved by the present application is to provide a low-reaction-threshold rare earth modified medium-entropy alloy by introducing rare earth elements into the medium-entropy alloy to improve the reaction threshold and energy release rate of the medium-entropy alloy.

[0006] The second technical problem to be solved by the present application is to provide a preparation method of a low-reaction-threshold rare earth modified medium-entropy alloy by introducing rare earth elements into the medium-entropy alloy to improve the reaction threshold and energy release rate of the medium-entropy alloy.

[0007] The technical scheme adopted by the present application to solve the first technical problem is as follows: a low reaction threshold value rare earth modified medium entropy alloy, characterized in that the low reaction threshold value rare earth modified medium entropy alloy is a TiZrTa medium entropy alloy, and the rare earth element used is Ce; the medium entropy alloy comprises the following components and their molar ratios:

[0008]

[0009] As a preferred embodiment, the medium entropy alloy comprises the following components and their molar ratios:

[0010]

[0011] As a best embodiment, the medium entropy alloy comprises the following components and their molar ratios:

[0012]

[0013] The technical scheme adopted by the present application to solve the second technical problem is as follows: a preparation method of a low reaction threshold value rare earth modified medium entropy alloy, characterized by comprising the following steps:

[0014] ①According to the designed ratio, Ti, Zr and Ta raw material powders are weighed and placed in a ball mill jar for mixing to obtain TiZrTa mixed powder;

[0015] ②The uniformly mixed TiZrTa mixed powder is filled into a container and vibrated;

[0016] ③The vibrated TiZrTa mixed powder is vacuum sintered and pre-alloyed to obtain a TiZrTa alloy block;

[0017] ④According to the designed ratio, the block rare earth Ce is weighed and placed in a crucible with the TiZrTa alloy block for vacuum high-frequency induction melting to obtain a product.

[0018] As a preferred embodiment, the particle size of the Ti powder in step ① is 10-60 μm, and the purity is ≥99.95%.

[0019] As a preferred embodiment, the particle size of the Zr powder in step ① is 45-74 μm, and the purity is ≥99.95%.

[0020] As a preferred embodiment, the particle size of the Ta powder in step ① is 30-50 μm, and the purity is ≥99.95%.

[0021] As a preferred embodiment, the ball milling conditions in step ① are as follows: the ball milling speed is 80-150 rpm, the ball-to-material ratio is 1:2-2:1, the ball milling time is 4-6 h, and the ball milling is carried out under inert gas protection.

[0022] As preferred, the vacuum sintering conditions in step 3 are as follows: sintering temperature 1000-1300℃, holding time 1-3h, vacuum degree ≤10Pa.

[0023] As preferred, the purity of the block rare earth Ce in step 4 is ≥99.9%.

[0024] As preferred, the vacuum high-frequency induction melting conditions in step 4 are as follows: vacuum degree ≤10Pa, heating power 15-25kW, melting time 2-5min.

[0025] Compared with the prior art, the application has the advantages that:

[0026] The rare earth element Ce is introduced into the TiZrTa middle-entropy alloy, the active components (Ti, Zr, Ta) of the TiZrTa middle-entropy alloy are ignited by the first reaction exothermic of the rare earth element at a low speed, the reaction threshold of the TiZrTa middle-entropy alloy is greatly reduced, and the application scenarios of the middle-entropy alloy energetic structural material are widened.

[0027] Under the promotion of the super-long combustion time of the rare earth element, the active components (Ti, Zr, Ta) of the TiZrTa middle-entropy alloy can realize sustained combustion energy release, the energy release rate of the TiZrTa middle-entropy alloy is significantly improved, and the damage power of the middle-entropy alloy energetic structural material is effectively improved.

[0028] The TiZrTa mixed powder does not need to be cold-pressed into a blank and can be sintered after being vibrated, so that the delamination and cracking of the blank in the cold-pressing demolding process are avoided. The pre-alloying of the TiZrTa alloy is realized through the vacuum sintering process, which helps to avoid casting defects and component volatilization caused by too large difference in melting points of components in the melting process. The uniform distribution and densification of the rare earth element in the TiZrTa alloy are realized through the vacuum high-frequency induction melting, and the process is simple and suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is an X-ray diffraction spectrum of the rare earth modified TiZrTa-Ce0.4 middle-entropy alloy in Example 1.

[0030] Figure 2 It is an SEM morphology diagram of the rare earth modified TiZrTa-Ce0.4 middle-entropy alloy in Example 1.

[0031] Figure 3 It is an ignition effect diagram of the rare earth modified TiZrTa-Ce0.4 middle-entropy alloy in Example 1 after impacting the aviation kerosene tank at 1000m / s.

[0032] Figure 4 It is an X-ray diffraction spectrum of the TiZrTa middle-entropy alloy in Comparative Example 1.

[0033] Figure 5 SEM morphology of the TiZrTa medium entropy alloy in Comparative Example 1.

[0034] Figure 6 Ignition effect diagram of the TiZrTa medium entropy alloy in Comparative Example 1 after impacting aviation kerosene tank at 1000 m / s. DETAILED DESCRIPTION

[0035] The application will be further described in conjunction with the following embodiments with reference to the accompanying drawings.

[0036] The following is a further elaboration of the application, but not a limitation of the application. The described embodiments are only a part of the embodiments of the application, but not all the embodiments; based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0037] In the following embodiments:

[0038] The purity of the metal elements Ti, Zr, Ta and the rare earth element Ce is greater than 99.9%, the particle size of the Ti powder is 10-60 μm, the particle size of the Zr powder is 45-74 μm, and the particle size of the Ta powder is 30-50 μm. First, a uniform TiZrTa mixed powder is obtained by a ball milling process, the ball milling speed is 80-150 rpm, the ball-to-material ratio is 1:2-2:1, and the ball milling time is 4-6 h; second, the powder is filled into a container and vibrated, and then pre-alloyed by vacuum sintering, the sintering temperature is 1000-1300 ℃, the holding time is 1-3 h, and the vacuum degree is ≤10 Pa; finally, the pre-alloyed TiZrTa alloy block and the Ce block are filled into a crucible, and a rare earth modified TiZrTa medium entropy alloy with a low reaction threshold is obtained by high-frequency induction melting, the vacuum degree of the high-frequency induction melting is ≤10 Pa, the heating power is 15-25 kW, and the melting time is 2-5 min.

[0039] Example 1

[0040] S1: Ti powder 149.6 g, Zr powder 285.0 g and Ta powder 565.4 g are weighed in a molar ratio of 1:1:1 and placed in a ball milling tank;

[0041] S2: 500 g of stainless steel grinding balls are added in a ball-to-material ratio of 1:2 based on the total mass of the raw material powder (including Ti powder, Zr powder and Ta powder);

[0042] S3: ball milling is carried out under inert atmosphere protection for 4 h at a ball milling speed of 100 rpm to obtain a uniform TiZrTa mixed powder;

[0043] S4: The TiZrTa mixed powder is filled into an alumina crucible and vibrated, and then is placed into a vacuum sintering furnace for pre-alloying, the sintering temperature is 1100 DEG C, the holding time is 2h, and the TiZrTa alloy block is obtained after furnace cooling;

[0044] S5: The rare earth Ce block 175.1g is weighed according to the proportion, and is placed into a smelting crucible together with the TiZrTa alloy block, high-frequency induction smelting equipment is used for smelting, the heating power is 24kW, the smelting time is 2min, and the rare earth modified TiZrTa-Ce 0.4 entropy alloy is obtained after furnace cooling to room temperature.

[0045] The rare earth modified TiZrTa-Ce 0.4 entropy alloy obtained in example 1 is subjected to X-ray diffraction, SEM and gun emission ignition aviation kerosene test, and the results are as follows:

[0046] Figure 1 It is the X-ray diffraction pattern of the rare earth modified TiZrTa entropy alloy obtained in example 1 of the application, according to the pattern, the main phase of the alloy is BCC phase, and a small amount of rare earth Ce and CeO diffraction peaks exist, which indicates that the introduction of Ce does not change the original phase composition of the TiZrTa entropy alloy.

[0047] Figure 2 It is the SEM morphology diagram of the rare earth modified TiZrTa entropy alloy obtained in example 1 of the application, wherein the BCC structure solid solution phase constitutes the alloy matrix, and the rare earth Ce is dispersedly distributed therein.

[0048] Figure 3 It is the ignition effect photo of the rare earth modified TiZrTa entropy alloy obtained in example 1 of the application on aviation kerosene at 1000m / s, the rare earth modified TiZrTa entropy alloy effectively penetrates the 6mm thick front steel plate, and then is broken into small fragments and shot into the inside of the oil tank, so that the aviation kerosene is ignited, the light is obvious, the reaction duration is more than 200ms, and excellent energy release characteristics are exhibited.

[0049] Comparative example 1

[0050] S1: Ti powder 149.6g, Zr powder 285.0g and Ta powder 565.4g are weighed according to the molar ratio of 1:1:1, and are placed in a ball mill jar;

[0051] S2: 500g of stainless steel grinding balls are added according to the ratio of the mass of the grinding balls to the total mass of the raw material powder (including Ti powder, Zr powder and Ta powder) of 1:2;

[0052] S3: Ball milling is carried out under inert atmosphere protection for 5h, the ball milling speed is 100rpm, and uniform TiZrTa mixed powder is obtained;

[0053] S4: fill the TiZrTa mixed powder into an alumina crucible and compact it, then put it into a vacuum sintering furnace for pre-alloying, the sintering temperature is 1100 DEG C, the holding time is 2h, and the TiZrTa alloy block is obtained after furnace cooling;

[0054] S5: put the TiZrTa alloy block into a smelting crucible, and use a high-frequency induction smelting device to smelt, the heating power is 24kW, the smelting time is 2min, and the dense TiZrTa medium-entropy alloy can be obtained after furnace cooling to room temperature.

[0055] Figure 4 The X-ray diffraction pattern of the TiZrTa medium-entropy alloy obtained in the present application comparative example 1, according to the pattern, the alloy is single-phase BCC structure.

[0056] Figure 5 The SEM morphology of the TiZrTa medium-entropy alloy obtained in the present application comparative example 1, the cross-section contrast of the alloy is uniform as a whole, and only a small amount of composition segregation exists.

[0057] Figure 6 The ignition effect diagram of the TiZrTa medium-entropy alloy obtained in the present application comparative example 1 on aviation kerosene at 1000m / s, the TiZrTa medium-entropy alloy effectively penetrates the 6mm thick front steel plate, the flame duration is 20ms, and the aviation kerosene cannot be effectively ignited, which proves that the TiZrTa medium-entropy alloy with rare earth has lower reaction threshold and more excellent energy release characteristics.

[0058] Example 2

[0059] S1: Ti powder 260.2g, Zr powder 248.0g and Ta powder 491.8g are weighed according to the molar ratio of 2:1:1, and are placed in a ball mill jar;

[0060] S2: 500g of grinding balls are added according to the ratio of grinding ball mass to total mass of raw material powder (including Ti powder, Zr powder and Ta powder) of 1:2;

[0061] S3: ball mill for 5h under inert atmosphere protection, the ball mill rotation speed is 100rpm, and the uniformly mixed TiZrTa mixed powder is obtained;

[0062] S4: fill the TiZrTa mixed powder into an alumina crucible and compact it, then put it into a vacuum sintering furnace for pre-alloying, the sintering temperature is 1100 DEG C, the holding time is 2h, and the TiZrTa alloy block is obtained after furnace cooling;

[0063] S5: weigh the rare earth Ce block 152.3g according to the proportion, and put it into the smelting crucible together with the Ti2ZrTa alloy block, use a high-frequency induction smelting device to smelt, the heating power is 24kW, the smelting time is 2min, and the rare earth modified Ti2ZrTa-Ce can be obtained after furnace cooling to room temperature.0.4 medium-entropy alloy.

[0064] The rare earth modified Ti2ZrTa-Ce 0.4 medium-entropy alloy obtained in Example 2 was subjected to X-ray diffraction, SEM, and gun launch ignition of aviation kerosene tests. The results show that the rare earth modified Ti2ZrTa-Ce 0.4 medium-entropy alloy is mainly a BCC phase, and a small amount of rare earth Ce and CeO also exist; the SEM image shows that the rare earth modified Ti2ZrTa-Ce 0.4 medium-entropy alloy obtained in Example 2 is a solid solution phase with a BCC structure, and the rare earth Ce is dispersedly distributed therein; the gun launch experiment proves that the rare earth modified Ti2ZrTa-Ce 0.4 medium-entropy alloy can effectively penetrate a 6mm-thick front steel plate at a speed of 800m / s, while achieving ignition of aviation kerosene, with obvious light and a reaction duration of more than 250ms, and excellent energy release characteristics.

[0065] Example 3

[0066] S1: Ti powder 260.2g, Zr powder 248.0g, and Ta powder 491.8g were weighed in a molar ratio of 2:1:1, and were placed in a ball mill jar;

[0067] S2: 500g of grinding balls were added in a ratio of grinding ball mass to total mass of raw material powder (including Ti powder, Zr powder, and Ta powder) of 1:2;

[0068] S3: under the protection of an inert atmosphere, the ball milling was carried out for 5h at a rotation speed of 100rpm, to obtain a uniformly mixed TiZrTa mixed powder;

[0069] S4: the TiZrTa mixed powder was filled into an alumina crucible and was vibrated and compacted, and was then placed in a vacuum sintering furnace for pre-alloying, with a sintering temperature of 1200℃ and a holding time of 1.5h, and after furnace cooling, a Ti2ZrTa alloy block was obtained;

[0070] S5: 76.2g of rare earth Ce block was weighed in proportion and was placed in a smelting crucible together with the Ti2ZrTa alloy block, and a high-frequency induction smelting device was used for smelting, with a heating power of 20kW and a smelting time of 3min, and after furnace cooling to room temperature, the rare earth modified Ti2ZrTa-Ce 0.2 medium-entropy alloy.

[0071] The rare earth modified Ti2ZrTa-Ce 0.2 medium-entropy alloy obtained in Example 3 was subjected to X-ray diffraction, SEM, and gun launch ignition of aviation kerosene tests. The results show that the rare earth modified Ti2ZrTa-Ce 0.2The main phase of the medium-entropy alloy is BCC phase, and a small amount of rare earth Ce and CeO exist; the SEM image shows that the rare earth modified Ti2ZrTa-Ce 0.2 The matrix phase of the medium-entropy alloy is a solid solution phase with BCC structure, and rare earth Ce is dispersedly distributed therein; gun launch tests prove that the rare earth modified Ti2ZrTa-Ce obtained in Example 3 0.2 The medium-entropy alloy can effectively penetrate a 6mm-thick front steel plate at a speed of 800m / s, while igniting aviation kerosene, the light is obvious, the reaction duration is more than 200ms, and the energy release characteristics are excellent.

[0072] Example 4

[0073] S1: Ti powder 149.6g, Zr powder 285.0g and Ta powder 565.4g were weighed in a molar ratio of 1:1:1 and placed in a ball mill jar;

[0074] S2: 500g of grinding balls were added in a ratio of 1:2 of the total mass of the grinding balls to the mass of the raw material powder (including Ti powder, Zr powder and Ta powder);

[0075] S3: Ball milling was carried out under inert atmosphere protection for 5h at a rotation speed of 100rpm to obtain a uniformly mixed TiZrTa mixed powder;

[0076] S4: The TiZrTa mixed powder was filled into an alumina crucible and vibrated, and then placed in a vacuum sintering furnace for pre-alloying, the sintering temperature was 1300℃, the holding time was 1h, and the TiZrTa alloy block was obtained after furnace cooling;

[0077] S5: Rare earth Ce block 218.9g was weighed in proportion and placed in a smelting crucible together with the TiZrTa alloy block, high-frequency induction smelting equipment was used for smelting, the heating power was 15kW, the smelting time was 5min, and the rare earth modified TiZrTa-Ce was obtained after furnace cooling to room temperature. 0.5 Medium-entropy alloy.

[0078] The rare earth modified TiZrTa-Ce obtained in Example 4 0.5 The medium-entropy alloy was tested by X-ray diffraction, SEM and gun launch test of aviation kerosene. The results show that the rare earth modified TiZrTa-Ce 0.5 The main phase of the medium-entropy alloy is BCC, and a small amount of rare earth Ce and CeO exist; the SEM image shows that the rare earth modified TiZrTa-Ce 0.5 The matrix phase of the medium-entropy alloy is a single-phase BCC structure, which is consistent with the XRD analysis result, and rare earth Ce is dispersedly distributed therein; gun launch tests prove that the rare earth modified TiZrTa-Ce obtained in Example 4 0.5The medium-entropy alloy can effectively penetrate a 6mm thick front steel plate at a speed of 800m / s, while achieving the ignition of aviation kerosene, the light is obvious, the reaction duration is more than 200ms, and the energy release characteristics are excellent.

[0079] Example 5

[0080] S1: Ti powder 208.5g, Zr powder 397.4g, and Ta powder 394.1g were weighed in a molar ratio of 1:1:0.5, and were placed in a ball mill jar;

[0081] S2: 500g of grinding balls were added in a ratio of grinding ball mass to total mass of raw material powder (including Ti powder, Zr powder, and Ta powder) of 1:2;

[0082] S3: Ball milling was carried out under inert atmosphere protection for 4h at a ball milling speed of 150rpm, and a uniformly mixed TiZrTa mixed powder was obtained;

[0083] S4: The TiZrTa mixed powder was filled into an alumina crucible and was vibrated and compacted, and then was placed into a vacuum sintering furnace for pre-alloying, the sintering temperature was 1100℃, and the holding time was 2h, and after furnace cooling, a TiZrTa 0.5 alloy bulk body was obtained;

[0084] S5: Rare earth Ce block 122.1g was weighed in proportion and was placed into a melting crucible together with the TiZrTa 0.5 alloy bulk body, high-frequency induction melting equipment was used for melting, the heating power was 24kW, the melting time was 2min, and after furnace cooling to room temperature, the rare earth modified TiZrTa 0.5 -Ce 0.2 medium-entropy alloy was obtained.

[0085] The rare earth modified TiZrTa 0.5 -Ce 0.2 medium-entropy alloy obtained in Example 5 was subjected to X-ray diffraction, SEM, and gun launch ignition of aviation kerosene tests. The results show that the rare earth modified TiZrTa 0.5 -Ce 0.2 medium-entropy alloy has a main phase of BCC+HCP, and a small amount of rare earth Ce and CeO also exists; the SEM image shows that the rare earth modified TiZrTa 0.5 -Ce 0.2 medium-entropy alloy has a main phase of BCC+HCP, and a small amount of rare earth Ce and CeO also exists; the SEM image shows that the rare earth modified TiZrTa 0.5 -Ce 0.2 medium-entropy alloy can effectively penetrate a 6mm thick front steel plate at a speed of 800m / s, while achieving the ignition of aviation kerosene, the light is obvious, the reaction duration is more than 200ms, and the energy release characteristics are excellent.

[0086] Example 6

[0087] S1: Ti powder 116.4 g, Zr powder 443.6 g, and Ta powder 440.0 g were weighed in a molar ratio of 1:2:1, respectively, and placed in a ball mill jar;

[0088] S2: 500 g of grinding balls were added in a ratio of 1:2 of the total mass of the grinding balls to the mass of the raw material powder (including Ti powder, Zr powder, and Ta powder);

[0089] S3: Ball milling was performed under inert atmosphere protection for 5 h at a rotation speed of 100 rpm to obtain a uniformly mixed TiZrTa mixed powder;

[0090] S4: The TiZrTa mixed powder was filled into an alumina crucible and vibrated, and then placed in a vacuum sintering furnace for pre-alloying. The sintering temperature was 1100°C, and the holding time was 2 h. After furnace cooling, a TiZr2Ta alloy block was obtained;

[0091] S5: Rare earth Ce block 68.1 g was weighed in proportion and placed in a smelting crucible together with the TiZr2Ta alloy block. High-frequency induction smelting equipment was used for smelting. The heating power was 24 kW, the smelting time was 2 min, and the furnace was cooled to room temperature to obtain the rare earth modified TiZr2Ta-Ce 0.2 entropy alloy.

[0092] The rare earth modified TiZr2Ta-Ce 0.2 entropy alloy obtained in Example 6 was subjected to X-ray diffraction, SEM, and gun launch ignition aviation kerosene tests. The results showed that the main phase of the rare earth modified TiZr2Ta-Ce 0.2 entropy alloy was BCC, and a small amount of rare earth Ce and CeO was also present; the SEM image showed that the matrix phase of the rare earth modified TiZr2Ta-Ce 0.2 entropy alloy was BCC phase, and rare earth Ce was dispersedly distributed therein; gun launch experiments confirmed that the rare earth modified TiZr2Ta-Ce 0.2 entropy alloy obtained in Example 6 could effectively penetrate a 6 mm thick front steel plate at a speed of 900 m / s, while igniting aviation kerosene, with obvious light and a reaction duration of more than 150 ms, and excellent energy release characteristics.

Claims

1. A low reaction threshold rare earth modified medium entropy alloy characterized by The low reaction threshold rare earth modified medium-entropy alloy is TiZrTa medium-entropy alloy, and the rare earth element is Ce; the medium-entropy alloy comprises the following components and their molar ratios:

2. The low-reaction-threshold rare-earth-modified medium-entropy alloy of claim 1, wherein The medium-entropy alloy comprises the following components and their molar ratios:

3. The low-reaction-threshold rare-earth-modified medium-entropy alloy of claim 2, wherein The medium-entropy alloy comprises the following components and their molar ratios:

4. A method of producing a low reaction threshold rare earth modified medium entropy alloy according to any one of claims 1 to 3, characterised by The method comprises the following steps: ①Ti, Zr and Ta raw material powders are weighed according to the designed ratio, mixed uniformly in a ball mill tank to obtain TiZrTa mixed powder; ②The uniformly mixed TiZrTa mixed powder is filled into a container and vibrated; ③The vibrated TiZrTa mixed powder is vacuum sintered and pre-alloyed to obtain a TiZrTa alloy block; ④The block rare earth Ce is weighed according to the designed ratio, and the Ce and the TiZrTa alloy block are put into a crucible for vacuum high-frequency induction melting to obtain a product.

5. The method of claim 4, wherein The Ti powder in step ① has a particle size of 10-60 μm and a purity of ≥99.95%.

6. The method of claim 4, wherein The Zr powder in step ① has a particle size of 45-74 μm and a purity of ≥99.95%.

7. The method of claim 4, wherein The Ta powder in step ① has a particle size of 30-50 μm and a purity of ≥99.95%.

8. The method of claim 4, wherein The ball milling conditions in step ① are as follows: ball milling speed 80-150 rpm, ball-to-material ratio 1:2-2:1, ball milling time 4-6 h, and inert atmosphere protection.

9. The method of claim 4, wherein The vacuum sintering conditions in step ③ are as follows: sintering temperature 1000-1300 ℃, holding time 1-3 h, and vacuum degree ≤10 Pa.

10. The method of claim 4, wherein The purity of the block rare earth Ce in step ④ is ≥99.9%.

11. The method of claim 4, wherein The vacuum high-frequency induction melting conditions in step ④ are as follows: vacuum degree ≤10 Pa, heating power 15-25 kW, and melting time 2-5 min.

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