Preparation method of short-process high-purity alloy with large melting point difference and low solid solubility

Abstract

The invention discloses a preparation method of a short-process high-purity alloy with large melting point difference and low solid solubility, which comprises a powder canning step, a vacuum treatment step and a finished product forming step, and adopts powder as a raw material, the composition proportion is flexible, the preparation process does not need a conventional sintering process or hot isostatic pressing, the forming and deformation processing are synchronous, the process is simple, convenient and efficient, and the production cost is low. The cost is low. The oxygen content of the powder in the sealed container is reduced by utilizing oxide decomposition balance, pressure reduction, temperature increase and oxide decomposition in the degassing stage, and the method has the main advantages that the powder material is purified, the oxygen content is smaller than 100 ppm, the purity is larger than or equal to 99%, short-process forming is achieved, and the product density is high.

Description

Technical Field

[0001] This invention relates to the field of production process technology for high-purity alloy materials, and in particular to a short-process method for preparing high-purity alloys with large melting point differences and low solid solubility. Background Technology

[0002] In the processing of alloy sputtering targets, if the melting points of the various metal elements in the target differ greatly and the solid solubility is low, it is difficult to form or control the compositional uniformity of the alloy sputtering target using traditional smelting methods. In addition, traditional smelting, sintering, hot isostatic pressing and other processes require a certain amount of raw materials to be fed into the furnace, resulting in high furnace start-up costs. Material compatibility can also cause microstructural defects such as microcracks, leading to a low yield of finished products. Using traditional powder metallurgy methods not only results in a long processing flow, but is also affected by the oxygen content of the powder raw materials. The oxygen content is usually above 1000 ppm, which cannot meet the technical requirement of an oxygen content of less than 800 ppm. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a short-process method for preparing high-purity alloys with large melting point differences and low solid solubility. This method not only has a short production cycle and low production cost, but also produces high-purity alloys with low oxygen content, fine and uniform internal grains, and no structural defects such as microcracks.

[0004] To achieve the above objectives, the technical solution adopted by this invention is: a short-process method for preparing high-purity alloys with large melting point differences and low solid solubility, comprising the following steps:

[0005] The powder filling process involves first mixing high-melting-point metal A and low-melting-point metal B to obtain a mixed powder, then filling the mixed powder into a metal can, sealing the metal can, and finally evacuating the can cavity through an evacuation port located in the metal can.

[0006] High-melting-point metal A is selected from metal powder with a purity of ≥99%, and low-melting-point metal B is selected from metal powder with a purity of ≥99%.

[0007] The difference in melting points between high-melting-point metal A and low-melting-point metal B is greater than 300℃.

[0008] The difference in atomic radii between high-melting-point metal A and low-melting-point metal B is greater than 15%.

[0009] The atomic percentage of the high-melting-point element in high-melting-point metal A is 0.01-50 at%, with the balance being low-melting-point metal B;

[0010] The vacuum processing steps include the following sub-steps:

[0011] The vacuum heating sub-step involves heating a metal can while maintaining a vacuum in the can cavity during the heating process, with the heating temperature below the melting point of the low-melting-point metal B.

[0012] The vacuum degassing step involves holding the container at a temperature for 4-8 hours and then cooling it to room temperature, maintaining a vacuum in the container cavity during both the holding and cooling processes.

[0013] The vacuum sealing sub-step involves welding and sealing the vent hole of the metal can immediately after completing the vacuum treatment sub-step, so that the inside of the can cavity is kept in a vacuum state for vacuum maintenance treatment.

[0014] The hot rolling forming sub-step involves heating the metal can to 400-1050℃ and then hot rolling the metal can.

[0015] In the final product step, after completing the vacuum holding process, the metal can is removed to obtain the alloy product.

[0016] Low-melting-point metal B forms the matrix of the alloy material, exhibiting good plasticity in deformation processing. High-melting-point metal A is dispersed, with a phase size ≤100µm.

[0017] The alloy products have a high material density of ≥99.8% and a purity of ≥99%. The average grain size of the alloy products is ≤100µm, the oxygen content is less than 100ppm, the internal grains are fine and uniformly distributed, and there is no segregation or coarse grain phenomenon caused by conventional melting or sintering.

[0018] In a further technical solution, the powder filling step,

[0019] First, place the high-melting-point metal A and the low-melting-point metal B into the mixing hopper of the mixing equipment.

[0020] Then, the mixing silo is evacuated.

[0021] After the vacuuming is completed, argon gas is then injected into the mixing silo.

[0022] Finally, a mixing process is performed to obtain a low-oxygen, high-purity mixed powder with an oxygen content of less than 800 ppm.

[0023] In a further technical solution, after argon gas is introduced into the mixing silo, the pressure inside the mixing silo is controlled at 0.1~1 MPa. The mixing process is protected by argon gas, and the mixing process time is 5~10 hours to obtain the mixed powder.

[0024] In a further technical solution, the powder filling step,

[0025] First, the mixed powder can is loaded into the cavity of the metal can, which has an opening on one side and is made of thin walls, and then the opening of the metal can is welded and sealed.

[0026] The wall thickness of the metal can is 1~10mm.

[0027] In a further technical solution, the mixing step,

[0028] The difference in melting points between the high-melting-point metal A and the low-melting-point metal B is greater than 500°C, and the difference in atomic radii between the high-melting-point metal A and the low-melting-point metal B is greater than 30%. The atomic percentage of the high-melting-point element in the high-melting-point metal A is 10-50 at%, with the remainder being the low-melting-point metal B.

[0029] In a further technical solution, the mixing step,

[0030] The average particle size of the high-melting-point metal A is 10-400µm;

[0031] The average particle size of the low-melting-point metal B is 10-400µm.

[0032] In a further technical solution, the vacuum heating sub-step involves heating a metal can while maintaining a vacuum in the can cavity during the heating process. The heating temperature is 200~600℃, and the heating time is 8~20H, to remove the gas adsorbed on the surface of the mixed powder in the can cavity.

[0033] The vacuum holding sub-step controls the vacuum level inside the tank cavity to be between 0.001 and 0.0001 Pa.

[0034] In a further technical solution, the hot rolling sub-step,

[0035] The metal can is placed in a muffle furnace and heated to 400-1050°C. After being held at this temperature for 2-6 hours, the metal can is subjected to hot rolling. The metal powder inside the metal can is rapidly densified, and residual gas inside the metal powder is squeezed out. While further reducing the oxygen content, densification is achieved through deformation, and the high-purity alloy is obtained inside the metal can.

[0036] In a further technical solution, in the mixing step, the high-melting-point metal A is selected from metals or alloys such as titanium, cobalt, silicon, or chromium, which have higher melting points, lower solid solubility, or poorer plasticity than the base metal, and the low-melting-point metal B is selected from metals or alloys such as copper or aluminum, which have lower melting points than metal A and good plasticity in deformation processing.

[0037] In a further technical solution, the vacuum heating sub-step is a stage that utilizes the decomposition equilibrium of oxides. In the vacuum heating stage, the pressure is reduced, the temperature is increased, and the oxides are decomposed. A metal can is used as a metal mold to reduce the oxygen content of the metal powder in a sealed container, achieving an oxygen content of <100ppm and a purity of ≥99% in terms of the purification of the metal powder.

[0038] The advantages of this invention compared to the prior art are:

[0039] 1. This invention uses high-purity powder as raw material, with flexible component ratio. The preparation process does not require conventional high-pressure molding and sintering processes. The process is simple and efficient, with a short production cycle and low production cost. Moreover, the high-purity alloy produced has low oxygen content, fine and uniform internal grains, and no structural defects such as microcracks.

[0040] 2. In the vacuum heating stage, this invention utilizes oxide decomposition equilibrium to reduce pressure, increase temperature, and decompose oxides, thereby reducing the oxygen content of powder in the sealed container. The main advantage is in material purification, with an oxygen content of <100ppm and a purity of ≥99%.

[0041] 3. This invention achieves densification through heating deoxidation, eliminating the need for sintering or smelting processes in traditional smelting methods. It employs direct hot deformation processing to form a dense structure. Compared to the traditional process that requires forming, sintering, and finally rolling, this invention is more efficient and lower in cost.

[0042] Based on the material composition ratio and matrix plasticity, this invention flexibly adopts forming methods such as hot rolling and extrusion, which can control the deformation rate and amount. While achieving dense forming of the material, it avoids structural defects such as microcracks. The high-purity alloy prepared has a material density of ≥99.8%, a material purity of ≥99%, an average grain size of ≤100µm, fine and uniformly distributed internal grains, and no segregation or coarse grain phenomenon caused by conventional melting or sintering. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0044] Figure 2 It is a metallographic diagram of a high-purity alloy made of 50 at% high-melting-point metal A and 50:50 at% low-melting-point metal B.

[0045] Figure 3 It is a metallographic diagram of a high-purity alloy made of 30 at% high-melting-point metal A and 70 at% low-melting-point metal B. Detailed Implementation

[0046] A short-process method for preparing high-purity alloys with large melting point differences and low solid solubility. Figure 1 As shown, it includes the following steps:

[0047] In the powder filling process, the high melting point metal A and the low melting point metal B are first placed into the mixing hopper of the mixing equipment, and then the mixing hopper is evacuated.

[0048] After vacuuming is completed, argon gas is injected into the mixing chamber. After the argon gas is injected into the mixing chamber, the pressure inside the mixing chamber is controlled at 0.1~1 MPa. The mixing process is protected by argon gas and the mixing time is 5~10 hours. After the mixing process, a low-oxygen, high-purity mixed powder is obtained, with an oxygen content of less than 800 ppm.

[0049] The mixed powder is then placed into a metal can. In this invention, the metal can is used as a melting mold. The metal can is a hollow can with one side open, made of thin walls. The wall thickness of the metal can is 1~10mm. Then the opening of the metal can is welded and sealed. An air extraction hole is set in the metal can to connect the can cavity. The air in the can cavity is removed by drawing a vacuum through the air extraction hole. Finally, the can cavity is evacuated by drawing a vacuum through the air extraction hole set in the metal can.

[0050] The metallic elements used in the preparation of high-purity alloys have unique characteristics, such as large differences in melting points and low solid solubility.

[0051] 1) The special characteristics of the metal elements in high-purity alloys: high-melting-point metal A is selected from metal powder with a purity of ≥99.9% and an average powder particle size of 10-400µm; low-melting-point metal B is selected from metal powder with a purity of ≥99% and an average powder particle size of 10-400µm.

[0052] The atomic percentage of the high-melting-point element in high-melting-point metal A is 0.01-50 at%, with the balance being low-melting-point metal B; specifically, the atomic percentage of the high-melting-point element in high-melting-point metal A is 10-50 at%, with the balance being low-melting-point metal B.

[0053] 2) The melting points differ greatly; the difference between the melting points of high-melting-point metal A and low-melting-point metal B is greater than 300℃.

[0054] 3) Low solid solubility; the difference in atomic radii between high-melting-point metal A and low-melting-point metal B is greater than 15%.

[0055] This invention is particularly applicable to the preparation of high-purity alloys in which the melting point difference between the high-melting-point metal A and the low-melting-point metal B is greater than 500°C and the atomic radius difference between the high-melting-point metal A and the low-melting-point metal B is greater than 30%. For example, the high-melting-point metal A is titanium, cobalt, silicon, or chromium, and the low-melting-point metal B is copper or aluminum.

[0056] The vacuum processing steps include the following sub-steps:

[0057] The vacuum heating sub-step involves heating a metal can while maintaining a vacuum in the can cavity during the heating process. The heating temperature is lower than the melting point of the low-melting-point metal B. Specifically, the metal can is heated while maintaining a vacuum in the can cavity during the heating process. The heating temperature is 200~600℃, and the heating time is 8~20H. This removes the gas adsorbed on the surface of the mixed powder in the can cavity. During the heating process, the vacuum degree in the can cavity is controlled at 0.001~0.0001 Pa.

[0058] The vacuum heating stage utilizes the decomposition equilibrium of oxides. In the vacuum heating stage, the pressure is reduced, the temperature is increased, and the oxides are decomposed. Using a metal can as a metal mold, the oxygen content of the metal powder is reduced in the sealed container. In terms of the purification of metal powder materials, the oxygen content is <100ppm and the purity is ≥99%.

[0059] The vacuum treatment sub-step involves controlling the vacuum level in the can cavity to 0.001~0.0001 Pa after the temperature inside the can cavity reaches 200~600℃, and maintaining the temperature for 4~8 hours to remove the gases adsorbed on the surface of the mixed powder inside the can cavity. The gases removed include oxygen. After the temperature maintenance is completed, the can cavity is naturally cooled to room temperature. The vacuum is maintained in the can cavity during the temperature maintenance and cooling processes.

[0060] The vacuum holding sub-step involves immediately welding and sealing the evacuation port of the metal can after the vacuum treatment sub-step is completed, so that the inside of the can cavity is kept in a vacuum state for vacuum holding treatment.

[0061] In the hot rolling step, the metal can is placed in a muffle furnace and heated to 400-1050°C. After holding at this temperature for 2-6 hours, the metal can is subjected to the hot rolling process. The metal powder inside the metal can is rapidly densified, and residual gases inside the metal powder are squeezed out. While further reducing the oxygen content, densification is achieved through deformation, and the high-purity alloy is obtained inside the metal can.

[0062] The final product process involves vacuum holding and cooling to room temperature before removing the metal container to obtain a high-purity alloy.

[0063] Low-melting-point metal B forms the matrix of the high-purity alloy, while high-melting-point metal A is dispersed, with a phase size ≤50µm.

[0064] High-purity alloys have a material density of ≥99.8% and a material purity of ≥99%. The average grain size of high-purity alloys is ≤100µm, the oxygen content is less than 100ppm, and the internal grains are fine and uniformly distributed without segregation or coarse grains produced by conventional melting or sintering.

[0065] According to the above preparation method, five samples were prepared: high-purity copper-titanium alloy, high-purity copper-molybdenum alloy, high-purity copper-cobalt alloy, high-purity aluminum-silicon alloy, and high-purity aluminum-chromium alloy. The test parameters of the five samples are shown in Table 1. The main difference is that different high-melting-point metal A powder and low-melting-point metal B were added in the mixing step.

[0066] Figure 2 The image shows a metallographic diagram of a high-purity alloy made of 50 at% high-melting-point metal A and 50:50 at% low-melting-point metal B. Figure 3 The image shows a metallographic diagram of a high-purity alloy made of 30 at% high-melting-point metal A and 70 at% low-melting-point metal B. The dark area represents the low-melting-point metal B, which forms the matrix, while the light area represents the high-melting-point metal A. The high-melting-point metal A is dispersed and has a phase size of tens of micrometers, which significantly improves the uniformity of the alloy composition and its overall performance. The degree of alloying is controlled through the process according to performance requirements.

[0067] The present invention also prepared high-purity copper-titanium alloy samples according to the above preparation method. In the mixing step, the weight ratio of copper to titanium is copper = 75 wt% : titanium = 25 wt%.

[0068] A high-purity copper-molybdenum alloy sample was prepared according to the above preparation method. In the mixing step, the weight ratio of copper to molybdenum was copper = 85 wt% : molybdenum = 15 wt%.

[0069] High-purity copper-cobalt alloy samples were prepared according to the above preparation method. In the mixing step, the weight ratio of copper to cobalt was 80 wt% copper : 20 wt% cobalt.

[0070] A high-purity aluminum-silicon alloy sample was prepared according to the above preparation method. In the mixing step, the weight ratio of copper to silicon was copper = 88 wt% : silicon = 12 wt%.

[0071] A high-purity aluminum-chromium alloy sample was prepared according to the above preparation method. In the mixing step, the weight ratio of copper to chromium was copper = 90 wt% : chromium = 10 wt%.

[0072]

[0073] Table 1 Performance Test Table

[0074] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing high-purity alloys with large melting point differences and low solid solubility through a short process, characterized in that: Includes the following steps, The powder filling process involves first mixing high-melting-point metal A and low-melting-point metal B to obtain a mixed powder, then filling the mixed powder into a metal can, sealing the metal can, and finally evacuating the can cavity through an evacuation port located in the metal can. High-melting-point metal A is selected from metal powder with a purity of ≥99%, and low-melting-point metal B is selected from metal powder with a purity of ≥99%. The difference in melting points between high-melting-point metal A and low-melting-point metal B is greater than 300℃. The difference in atomic radii between high-melting-point metal A and low-melting-point metal B is greater than 15%. The atomic percentage of the high-melting-point element in high-melting-point metal A is 0.01-50 at%, with the balance being low-melting-point metal B; The vacuum treatment process includes the following sub-steps: The vacuum heating sub-step involves heating a metal can while maintaining a vacuum in the can cavity during the heating process, with the heating temperature below the melting point of the low-melting-point metal B. The vacuum degassing step involves holding the container at a temperature for 4-8 hours and then cooling it to room temperature, maintaining a vacuum in the container cavity during both the holding and cooling processes. The vacuum sealing sub-step involves welding and sealing the vent hole of the metal can immediately after completing the vacuum treatment sub-step, so that the inside of the can cavity is kept in a vacuum state for vacuum maintenance treatment. The hot rolling forming sub-step involves heating the metal can to 400-1050℃ and then hot rolling the metal can. In the final product step, after completing the vacuum holding process, the metal can is removed to obtain the alloy product. Low-melting-point metal B forms the matrix of the alloy material, exhibiting good plasticity in deformation processing. High-melting-point metal A is dispersed, with a phase size ≤100µm. The alloy products have a high material density of ≥99.8% and a purity of ≥99%. The average grain size of the alloy products is ≤100µm, the oxygen content is less than 100ppm, the internal grains are fine and uniformly distributed, and there is no segregation or coarse grain phenomenon caused by conventional melting or sintering.

2. The method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to claim 1, characterized in that: The powder packaging step First, place the high-melting-point metal A and the low-melting-point metal B into the mixing hopper of the mixing equipment. Then, the mixing silo is evacuated. After the vacuuming is completed, argon gas is then injected into the mixing silo. Finally, a mixing process is performed to obtain a low-oxygen, high-purity mixed powder with an oxygen content of less than 800 ppm.

3. The method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to claim 2, characterized in that: After argon gas is introduced into the mixing chamber, the pressure inside the mixing chamber is controlled at 0.1~1 MPa. The mixing process is carried out under argon gas protection and the mixing time is 5~10 hours to obtain the mixed powder.

4. The method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to claim 1, characterized in that: The powder packaging step First, the mixed powder can is loaded into the cavity of the metal can, which has an opening on one side and is made of thin walls, and then the opening of the metal can is welded and sealed. The wall thickness of the metal can is 1~10mm.

5. The method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to claim 1, characterized in that: The mixing step, The difference in melting points between the high-melting-point metal A and the low-melting-point metal B is greater than 500°C, and the difference in atomic radii between the high-melting-point metal A and the low-melting-point metal B is greater than 30%. The atomic percentage of the high-melting-point element in the high-melting-point metal A is 10-50 at%, with the remainder being the low-melting-point metal B.

6. The method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to claim 1, characterized in that: The mixing step, The average particle size of the high-melting-point metal A is 10-400µm; The average particle size of the low-melting-point metal B is 10-400µm.

7. The method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to claim 1, characterized in that: The vacuum heating sub-step involves heating a metal can while maintaining a vacuum in the can cavity during the heating process. The heating temperature is 200~600℃, and the heating time is 8~20H, to remove the gas adsorbed on the surface of the mixed powder inside the can cavity. The vacuum holding sub-step controls the vacuum level inside the tank cavity to be between 0.001 and 0.0001 Pa.

8. The method for preparing a short-process high-purity alloy with large melting point difference and low solid solubility according to claim 1, characterized in that: The hot rolling sub-step, The metal can is placed in a muffle furnace and heated to 400-1050°C. After being held at this temperature for 2-6 hours, the metal can is subjected to hot rolling. The metal powder inside the metal can is rapidly densified, and residual gas inside the metal powder is squeezed out. While further reducing the oxygen content, densification is achieved through deformation, and the high-purity alloy is obtained inside the metal can.

9. A method for preparing a short-process high-purity alloy with large melting point differences and low solid solubility according to any one of claims 1 to 8, characterized in that: In the mixing step, the high-melting-point metal A is selected from metals or alloys such as titanium, cobalt, silicon, or chromium, which have higher melting points, lower solid solubility, or poorer plasticity than the base metal. The low-melting-point metal B is selected from metals or alloys such as copper or aluminum, which have lower melting points than metal A and good plasticity in deformation processing.

10. The method for preparing a short-process high-purity alloy with large melting point difference and low solid solubility according to claim 9, characterized in that: The vacuum heating sub-step utilizes the decomposition equilibrium of oxides. In the vacuum heating stage, the pressure is reduced, the temperature is increased, and the oxides are decomposed. Using a metal can as a metal mold, the oxygen content of the metal powder is reduced in the sealed container, achieving an oxygen content of <100ppm and a purity of ≥99% in terms of the purification of the metal powder.

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