High-density titanium-based alloy rotating target material and preparation method thereof

Abstract

The invention belongs to the field of target materials, and particularly relates to a high-density titanium-based alloy rotating target material and a preparation method thereof. The high-density titanium-based alloy rotating target material is combined on the outer side surface of a titanium-based back pipe, and comprises more than about 50 at% to about 99 at% of metallic titanium and about 1 at% to less than about 50 at% of refractory elements based on the total atom amount of the titanium-based alloy rotating target material, wherein the melting point of the refractory element simple substance is higher than that of the metal titanium simple substance. The high-density titanium-based alloy rotating target material disclosed by the invention has relatively high target material relative density and relatively high material utilization rate, and the titanium-based back tube and the titanium-based alloy rotating target material are well combined.

Description

Technical Field

[0001] The invention belongs to the field of target materials, and in particular relates to a high-density titanium-based alloy rotating target material and a preparation method thereof. Background Art

[0002] Titanium and its alloy targets are widely used in liquid crystal display materials, solar cells, magnetic materials and other fields. As basic materials, they play a key role.

[0003] Titanium-based alloy targets are mainly based on titanium (Ti), in which the content of Ti atoms is generally higher than about 50at%. Titanium-based alloy targets can be prepared by adding some alloy elements with special functions (such as refractory metal elements such as tungsten (W), molybdenum (Mo), tantalum (Ta) and / or chromium (Cr).

[0004] For titanium-based alloy flat targets (round or square), generally, an ingot is first produced by a special powder metallurgy process such as hot isostatic pressing, hot pressing, hot extrusion, etc., and then the target is produced by machining.

[0005] Titanium-based alloy tubular rotating targets are currently mainly prepared by plasma spraying, that is, titanium powder and alloy powder with a certain alloy ratio and particle size are mixed in a certain proportion to obtain a mixed powder, and then a rotating target with a certain size is prepared by plasma spraying. The targets prepared by this process have the following disadvantages: 1. The alloy ratio deviation of the prepared target is large; 2. The material utilization rate is low during the target preparation process; 3. The relative density of the target is low.

[0006] Therefore, there is still a strong demand in the prior art for preparing high-density titanium-based alloy rotary targets with higher material utilization. Summary of the invention

[0007] Purpose of the Invention

[0008] In view of the problems existing in the prior art described in the above background technology section, an object of the present invention is to provide a high-density titanium-based alloy rotary target and a preparation method thereof.

[0009] Technical Solution

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] Solution 1: A high-density titanium-based alloy rotating target material bonded to the outer side of a titanium-based back tube, wherein the titanium-based alloy rotating target material comprises or consists of the following substances:

[0012] Based on the total amount of atoms of the titanium-based alloy rotating target:

[0013] About >50 at % to about 99 at % metallic titanium, and

[0014] About 1 at % to about <50 at % of a refractory element, wherein the melting point of the refractory element alone is higher than the melting point of metallic titanium.

[0015] Option 2: A high-density titanium-based alloy rotary target according to Option 1 above, wherein the refractory element comprises a refractory metal element.

[0016] Option 3: A high-density titanium-based alloy rotary target according to Option 2 above, wherein the refractory metal element comprises one or more of tungsten, molybdenum, tantalum, vanadium, niobium and chromium.

[0017] Option 4: A high-density titanium-based alloy rotary target according to any one of the above options 1 to 3, wherein the titanium-based backing tube contains greater than about 50at%, preferably greater than about 80at%, of metallic titanium based on the total amount of atoms in the titanium-based backing tube.

[0018] Option 5: A high-density titanium-based alloy rotary target according to any one of the above options 1 to 4, wherein the material of the titanium-based back tube is selected from Ta1, Ta2 or Tc4 titanium alloy.

[0019] Option 6: A high-density titanium-based alloy rotary target according to any one of Options 1 to 5 above, wherein the target relative density of the titanium-based alloy rotary target is greater than about 99%.

[0020] Option 7: A high-density titanium-based alloy rotary target according to any one of the above options 1 to 5, wherein the material utilization rate of the titanium-based alloy rotary target is greater than about 50%.

[0021] Scheme 8: A method for preparing a high-density titanium-based alloy rotary target according to any one of Schemes 1 to 7 above, wherein the method comprises the following steps:

[0022] Step 1: providing a mixed powder comprising a titanium metal powder having a particle size in the range of about >50 to about 150 μm and a refractory element powder having a particle size in the range of about 5 to about 50 μm, wherein the proportion of the titanium metal powder is about >50 at % to about 99 at % based on the total amount of atoms of the mixed powder.

[0023] at%, the proportion of the refractory element powder is about 1 at% to about <50 at%;

[0024] Step 2: Load the mixed powder into a sheath mold, wherein the sheath mold comprises an outer sheath and a titanium-based inner liner tube.

[0025] Step 3: sequentially performing degassing treatment and hot isostatic pressing treatment on the mixed powder in the sheathing mold, so as to obtain a titanium-based alloy tube target ingot blank with the titanium-based inner liner tube as the back tube;

[0026] and

[0027] Step 4: Machining the titanium-based alloy tube target ingot obtained in step 3 to remove the outer sheath, thereby obtaining the high-density titanium-based alloy rotary target material combined with the titanium-based backing tube.

[0028] Option 9: A preparation method according to Option 8 above, wherein the titanium-based inner liner tube contains greater than about 50 at%, preferably greater than about 80 at%, of metallic titanium based on the total amount of atoms in the titanium-based backing tube.

[0029] Option 10: A preparation method according to Option 8 or 9 above, wherein the material of the titanium-based liner tube is selected from Ta1, Ta2 or Tc4 titanium alloy.

[0030] Scheme 11: The preparation method according to any one of Schemes 8 to 10, wherein the degassing treatment comprises: -3 The degassing is carried out at a pressure of Pa and a temperature of about 300 to about 500° C. for at least about 4 hours.

[0031] Scheme 11: A preparation method according to any one of Schemes 8 to 11 above, wherein the hot isostatic pressing treatment comprises hot isostatic pressing at a pressure of about 90 to about 150 MPa and a temperature of about >850 to about 1000°C for about 1 to about 5 hours.

[0032] Scheme 12: A preparation method according to any one of Schemes 8 to 11 above, wherein the refractory element powder comprises refractory metal element powder.

[0033] Option 13: A preparation method according to any one of the above options 8 to 12, wherein the refractory element powder comprises one or more of tungsten, molybdenum, tantalum, vanadium, niobium, chromium powder and alloy powders composed of one or more of these refractory metal elements.

[0034] Scheme 14: A preparation method according to any one of Schemes 8 to 13 above, wherein the outer sheath contains greater than about 50 at %, preferably greater than about 80 at %, of metallic titanium based on the total amount of atoms in the titanium-based backing tube.

[0035] Option 15: A preparation method according to any one of the above options 8 to 14, wherein the material of the outer sheath is selected from Ta1, Ta2 or Tc4 titanium alloy.

[0036] Scheme 16: A preparation method according to any one of schemes 8 to 15 above, wherein the relative density of the mixed powder loaded into the encapsulation mold in step 2 is in the range of about 40 to about 70%.

[0037] Technical Effects

[0038] The high-density titanium-based alloy rotating target material of the present invention has relatively high density and high material utilization rate, and the titanium-based backing tube is well combined with the titanium-based alloy rotating target material.

[0039] Specifically, the present invention selects a sheath and an inner liner of pure Ti or Ti alloy, utilizes a hot isostatic pressing (HIP) process at about >850 to about 1000°C, and uses a Ti powder raw material with a particle size of about >50 to about 150 μm to prepare a titanium-based alloy rotating target with high relative density, high material utilization, and good bonding between the liner and the Ti substrate.

[0040] In addition, the cold molding → cold isostatic pressing → hot isostatic pressing → machining molding process commonly used in the prior art is relatively long and complicated, and the process cost will be very high. Compared with the process of the prior art, the present invention optimizes the powder particle size and adopts the preferred sleeve and liner tube design method to directly realize the molding by hot isostatic pressing after powder filling and degassing. Therefore, the present invention has more advantages than the prior art, does not require primer, can be directly loaded with powder for application, and the overall process is simpler and more efficient. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without paying creative work belong to the scope of protection of the present invention. The process parameters of the following embodiments that do not specify specific conditions are usually based on normal conditions.

[0042] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. The term "about" used in the present invention means that the modified numeral can fluctuate within the range of ±20%, ±15%, ±10%, ±5% or ±2% of the numeral. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in the present invention.

[0043] According to a first aspect of the present invention, the present invention provides a high-density titanium-based alloy rotary target material, wherein the target material is bonded to the outer side surface of a titanium-based back tube.

[0044] The high-density titanium-based alloy rotary target according to the first aspect of the present invention comprises or consists of the following substances:

[0045] Based on the total amount of atoms of the titanium-based alloy rotating target:

[0046] about >50 at%, such as about 60 at%, about 70 at%, about 80 at%, about 85 at%, about 90 at%, about 95 at% or about 99 at% of metallic titanium, and

[0047] About <50 at%, such as about 40 at%, about 30 at%, about 20 at%, about 15 at%, about 10 at%, about 5 at% or about 1 at% of a refractory element, wherein the melting point of the refractory element alone is higher than the melting point of metallic titanium.

[0048] In some exemplary embodiments of the present invention, the refractory element may be a refractory metal element, wherein the refractory metal element includes but is not limited to one or more of tungsten, molybdenum, tantalum, vanadium, niobium and chromium.

[0049] In other exemplary embodiments of the present invention, the titanium-based back tube contains greater than about 50 at%, preferably greater than about 80 at%, of metallic titanium based on the total amount of atoms of the titanium-based back tube. The higher the titanium content in the titanium-based back tube selected in the present invention, the stronger the bonding between the titanium-based back tube and the titanium-based alloy rotating target; when the titanium content in the titanium-based back tube is less than about 50 at%, the back tube and the target may not be able to diffuse well with each other to form a metallurgical bond, so the interface between them may be prone to cracking (see the comparative example below, when 304 stainless steel tube is selected as the back tube, the target and the back tube cannot diffuse and bond, and the interface cracks). Therefore, when a material close to the titanium matrix in the target is selected, diffusion welding of the two can be achieved only through a high temperature and high pressure process of hot isostatic pressing, and the processed finished product has an excellent welding layer, and the bonding is firm and does not crack.

[0050] In some particularly preferred embodiments of the present invention, the titanium-based back tube can be made of Ta1, Ta2 or Tc4 titanium alloy.

[0051] The high-density titanium-based alloy rotary target according to the first aspect of the present invention may have, for example, a target relative density greater than about 99%, such as greater than about 99.2%, preferably greater than about 99.3% or even greater than about 99.5%.

[0052] The high density titanium-based alloy rotary target according to the first aspect of the present invention may also have a material utilization rate greater than about 50%, such as greater than about 53%, preferably greater than about 55% or even greater than about 58%.

[0053] According to a second aspect of the present invention, the present invention provides a method for preparing a high-density titanium-based alloy rotary target according to the first aspect of the present invention, wherein the method comprises steps 1 to 4 below.

[0054] The step 1 includes providing a mixed powder comprising titanium metal powder and refractory element powder.

[0055] In the mixed powder provided in step 1, based on the total amount of atoms of the mixed powder, the proportion of the titanium metal powder is greater than about 50at%, for example, greater than about 60at%, greater than about 70at%, greater than about 80at%, greater than about 85at%, greater than about 90at% or even greater than about 99at%; and the weight proportion of the refractory element powder is less than about 50at%, for example, less than about 40at%, less than about 30at%, less than about 20at%, less than about 15at%, less than about 10at%, less than about 5at% or even less than about 1at%.

[0056] In addition, in the mixed powder provided in step 1, the particle size of the titanium metal powder is in the range of about >50 to about 150 μm, for example, about 60 μm, about 75 μm, about 100 μm or about 125 μm. Here, the particle size of the titanium metal powder should not be too large, for example, it should not exceed about 150 μm, otherwise it may increase the difficulty of mixing, and the titanium metal powder and the refractory element powder may be mixed unevenly, and the target material finally prepared may be partially segregated and unqualified; in addition, the particle size of the titanium metal powder should not be too small, for example, it should not be less than about 50 μm, otherwise it may cause the material utilization rate to be too low.

[0057] In addition, in the mixed powder provided in step 1, the particle size of the refractory metal itself is difficult to increase. Generally, the particle size of commercially available refractory element powder is usually in the range of about 5 to about 50 μm, such as about 10 μm, about 20 μm, about 30 μm or about 40 μm. Here, when the particle size of the refractory metal is too large, it is easy to cause uneven powder mixing and agglomeration of refractory particles in the target material. If the particle size is too small, the powder making process cost may be relatively high, and the impurities such as oxygen content in the powder may be relatively high.

[0058] In the above step 1, the refractory element powder may include refractory metal element powder, wherein the refractory metal element powder may include but is not limited to one or more of tungsten, molybdenum, tantalum, vanadium, niobium, chromium powder and alloy powders composed of one or more of these refractory metal elements.

[0059] The step 2 includes loading the mixed powder into a sheathing mold, wherein the sheathing mold includes an outer sheath and a titanium-based inner liner tube. Specifically, the mixed powder is loaded into a space formed between the outer sheath and the titanium-based inner liner tube.

[0060] In the step 2, the titanium-based inner liner tube may contain greater than about 50at%, preferably greater than about 80at%, of metallic titanium based on the total amount of atoms of the titanium-based inner liner tube. The titanium-based backing tube selected here will eventually become the titanium-based backing tube combined with the high-density titanium-based alloy rotating target of the present invention. As mentioned above, the higher the titanium content in the titanium-based backing tube, the stronger the bond between the titanium-based backing tube and the titanium-based alloy rotating target; when the titanium content in the titanium-based backing tube is less than about 50at%, the backing tube and the target material cannot diffuse well with each other to form a metallurgical bond, so the interface between them is prone to cracking. Similarly, in some particularly preferred embodiments of the present invention, the titanium-based backing tube can be selected from Ta1, Ta2 or Tc4 titanium alloy backing tubes.

[0061] In step 2, the outer sheath is preferably made of the same material as the titanium-based inner liner. That is, the outer sheath also contains more than about 50 at%, preferably more than about 80 at%, of metallic titanium based on the total amount of atoms in the outer sheath. Similarly, in some particularly preferred embodiments of the present invention, the outer sheath can be made of Ta1, Ta2 or Tc4 titanium alloy.

[0062] In addition, in the process of preparing and sealing the sheath mold, it is preferred to use a titanium-based solder for sealing. For example, a solder made of the same material as the outer sheath and the titanium-based inner liner tube can be used for sealing.

[0063] In addition, in the process of loading the mixed powder into the encapsulation mold, the relative density of the mixed powder can be in the range of about 40 to about 70%, such as about 45%, about 50%, about 55%, about 60% or about 65%. Here, the term "relative density of powder loading" means: the ratio of the actual loading density of the powder loaded into the encapsulation to the actual density of the dense material. It is well known in the art that the loading density refers to the weight of the powder material loaded in a specified volume; for powder materials, the loading density of materials of different particle sizes will be different. The finer the powder, the easier it is to form "bridges" and other phenomena between the particles, and it is more difficult to fill densely. The weight of the powder finally loaded into the container is lighter, that is, the loading density is lower. Here, the relative density of the mixed powder loaded into the encapsulation mold generally does not exceed about 70%, unless it is pre-pressed into blocks before loading, which will lead to complex processes and increased costs.

[0064] The step 3 includes sequentially performing degassing treatment and hot isostatic pressing treatment on the mixed powder in the sheathing mold, so as to obtain a titanium-based alloy tube target ingot blank with the titanium-based liner tube as the back tube.

[0065] It is well known that there may be gas and moisture in the mixed powder. During hot isostatic pressing, these substances may affect the stability and uniformity of the hot isostatic pressing process, thereby causing defects and performance degradation of the final product, such as affecting the density, strength and corrosion resistance of the final product. Here, the purpose of the degassing treatment is to remove these gases and moisture that may exist in the mixed powder. If hot isostatic pressing is performed directly without degassing, there will be air in the package. The relative density of the target material will be relatively low after hot isostatic pressing, and defects such as voids may also be formed inside the target material due to the presence of air.

[0066] The process parameters of the degassing treatment can be adjusted by a person skilled in the art according to the charging conditions and the indicators to be achieved. For example, in some exemplary embodiments of the present invention, the degassing treatment includes heating the mixed powder at a temperature of about ≤2×10 -3 Pa and a temperature of about 300 to about 500° C. (eg, about 350° C., about 400° C., or about 450° C.) for at least about 4 hours (eg, about 6 hours or about 8 hours).

[0067] In addition, the hot isostatic pressing can be performed directly after the degassing process without other process steps. Since the present invention adopts an optimized powder particle size and an optimal design of the jacket and the inner liner, the molding can be directly achieved by hot isostatic pressing only after powder filling and degassing.

[0068] The process conditions of the hot isostatic pressing treatment need to match the material to be hot pressed, so as to obtain the desired high-density titanium-based alloy rotary target. For example, in some exemplary embodiments of the present invention, the isostatic pressing treatment includes hot isostatic pressing at a pressure of about 90 to about 150 MPa (e.g., about 110 MPa, about 125 MPa, or about 130 MPa) and a temperature of about >850 to about 1000°C (e.g., about 900°C or about 950°C) for about 1 to about 5 hours (e.g., about 2 hours, about 3 hours, or about 4 hours).

[0069] The present invention is further described in detail below with reference to specific embodiments and comparative examples.

[0070] Examples 1-7 and Comparative Examples 1-6: General method for preparing titanium-based alloy rotary targets

[0071] (1) Titanium metal powder and one or more refractory element powders are fully mixed in a three-dimensional mixer according to the process parameters shown in Table 1 to obtain a mixed powder.

[0072] (2) The mixed powder is loaded into a sheath mold. The materials of the outer sheath and inner liner of the sheath mold are also shown in Table 1. The sheath needs to be sealed with a titanium-based welding material;

[0073] (3) The encapsulating mold filled with the mixed powder is subjected to a vacuum degassing treatment in a heating furnace. The process parameters of the degassing treatment are shown in Table 1;

[0074] (4) The degassed mold is placed in a hot isostatic pressing furnace for hot isostatic pressing to obtain a titanium-based alloy rotary target ingot. The process parameters of the hot isostatic pressing are shown in Table 1.

[0075] (5) The titanium-based alloy rotary target ingot is machined to remove the outer sheath, and then precision-processed to obtain the titanium-based alloy rotary target.

[0076] Table 1:

[0077]

[0078] Table 1 (continued):

[0079]

[0080] The titanium-based alloy rotary targets obtained from Examples 1 to 7 and Comparative Examples 1 to 6 were quality inspected, and the inspection results are shown in Table 2. The relative density of the finished target in Table 2 is the ratio of the actual measured density of the material to the theoretical density, and the actual density is measured by the Archimedean drainage method; the material utilization rate is obtained by the weight of the target after the target is processed into the finished product and the weight of the raw material loaded into the sleeve mold; the interface bonding between the target and the liner can be analyzed by microscopic observation to observe the interface bonding between the target and the backing tube to check whether there are cracks, gaps, etc.

[0081] Table 2:

[0082]

[0083] It can be seen from the performance results of Examples 1 to 2 and Comparative Examples 1 to 2 that the selection of titanium metal powders with different particle sizes has an important influence on the performance results of the prepared target material, that is, as the particle size of the titanium metal powder decreases, the relative density of the powder in the sheath also decreases, so that a larger sheath size needs to be designed, which will lead to a lower material utilization rate of the final target material. For example, in Comparative Example 1, the particle size of the titanium metal powder is relatively small (about 50 μm), the relative density of the powder is low (about 37.5%), the sheath design is large, and the shrinkage non-uniformity after HIP is also large. Therefore, a large amount of machining is required after HIP to turn it into a finished product, so its material utilization rate is low (about 38.6%). When the particle size of the titanium metal powder is further reduced to about 30 μm (Comparative Example 2), the relative density of the powder in the sheath is only about 29%, the packing density is too low, the ingot shrinks too much during the HIP process, the outer sheath mold cracks, and the ingot is scrapped. Therefore, too small a particle size of the titanium metal powder will lead to too low a material utilization rate.

[0084] It can be seen from the performance results of Examples 3 to 4 and Comparative Examples 3 and 6 that as the HIP temperature increases, the density of the target material becomes higher and higher. When the HIP temperature is higher than about 850°C, the density of the target material can reach more than about 99% (see the results of Examples 3 and 4), while when the HIP temperature is lower than about 850°C, the relative density of the target material cannot reach about 99% (see the results of Comparative Examples 3 and 6).

[0085] It can be seen from the performance results of Example 4 and Comparative Example 4 and the performance results of Example 5 and Comparative Example 5 that the conventional 304 stainless steel or 45# steel selected for the sheath and the liner tube cannot achieve a good interface bonding between the liner tube and the titanium-based alloy rotating target layer, resulting in cracking, making the finished target material unusable.

[0086] It can be seen from the performance results of Example 7 that when the composite powder is used as the refractory element powder, a titanium-based alloy rotary target with good performance can still be obtained.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A high-density titanium-based alloy rotating target material bonded to the outer side of a titanium-based back tube, characterized in that: The titanium-based alloy rotary target material comprises the following substances or consists of the following substances: Based on the total amount of atoms of the titanium-based alloy rotating target: >50at% to 99at% metallic titanium, and 1 at% to <50 at% of a refractory element, wherein the melting point of the refractory element alone is higher than the melting point of metallic titanium.

2. The high-density titanium-based alloy rotary target according to claim 1, characterized in that: The refractory element comprises one or more of the refractory metal elements tungsten, molybdenum, tantalum, vanadium, niobium and chromium.

3. The high-density titanium-based alloy rotary target according to claim 1 or 2, characterized in that: The material of the titanium-based back tube is selected from Ta1, Ta2 or Tc4 titanium alloy.

4. The high-density titanium-based alloy rotary target according to claim 1 or 2, characterized in that: The target relative density of the titanium-based alloy rotary target is greater than 99%; and / or The material utilization rate of the titanium-based alloy rotary target is greater than 50%.

5. A method for preparing a high-density titanium-based alloy rotary target according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Step 1: providing a mixed powder comprising titanium metal powder having a particle size in the range of >50 to 150 μm and refractory element powder having a particle size in the range of 5 to 50 μm, wherein based on the total amount of atoms of the mixed powder, the proportion of the titanium metal powder is >50 at% to 99 at%, and the proportion of the refractory element powder is 1 at% to <50 at%; Step 2: Load the mixed powder into a sheath mold, wherein the sheath mold comprises an outer sheath and a titanium-based inner liner tube. Step 3: sequentially performing degassing treatment and hot isostatic pressing treatment on the mixed powder in the sheathing mold, so as to obtain a titanium-based alloy tube target ingot blank with the titanium-based inner liner tube as the back tube; and Step 4: Machining the titanium-based alloy tube target ingot obtained in step 3 to remove the outer sheath, thereby obtaining the high-density titanium-based alloy rotary target material combined with the titanium-based backing tube.

6. The preparation method according to claim 5, characterized in that: The material of the titanium-based liner tube is selected from Ta1, Ta2 or Tc4 titanium alloy.

7. The preparation method according to claim 5 or 6, characterized in that: The degassing treatment comprises heating the mixed powder at ≤2×10 -3 Degassing at a pressure of Pa and a temperature of 300 to 500°C for at least 4 hours; and / or The hot isostatic pressing treatment includes hot isostatic pressing at a pressure of 90 to 150 MPa and a temperature of >850 to 1000° C. for 1 to 5 hours.

8. The preparation method according to claim 5 or 6, characterized in that: The refractory element powder includes one or more of refractory metal elements tungsten, molybdenum, tantalum, vanadium, niobium, chromium powder and alloy powder composed of one or more of these refractory metal elements.

9. The preparation method according to claim 5 or 6, characterized in that: The outer sheath material is selected from Ta1, Ta2 or Tc4 titanium alloy.

10. The preparation method according to claim 5 or 6, characterized in that: The relative density of the mixed powder loaded into the encapsulation mold in step 2 is in the range of 40 to 70%.

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