A method for electron beam additive manufacturing of polycrystalline feedstock rods for molybdenum-rhenium alloy single crystal production

Abstract

The application discloses a polycrystalline raw material rod electron beam additive manufacturing method for molybdenum-rhenium alloy single crystal preparation, and comprises the following steps: 1, preparing a mixed powder of molybdenum-rhenium alloy; 2, cold isostatic pressing; 3, sintering; 4, spinning and wire drawing; 5, alkali washing and ethanol cleaning; 6, electron beam melting wire additive manufacturing; 7, using the molybdenum-rhenium alloy polycrystalline raw material rod for electron beam suspension zone melting to prepare molybdenum-rhenium alloy single crystal material. The application directly spins and draws after cold isostatic pressing and sintering, and then prints the molybdenum-rhenium alloy polycrystalline raw material rod by electron beam additive manufacturing, avoids the multiple melting and subsequent extrusion process links in the prior art, greatly improves the raw material utilization rate and reduces the manufacturing cost, solves the problems of extremely long manufacturing process cycle, extremely low raw material utilization rate and extremely high manufacturing cost of the current polycrystalline raw material rod for molybdenum-rhenium alloy single crystal preparation, and replaces the manufacturing technology of the existing raw material rod in the molybdenum-rhenium alloy single crystal preparation process.

Description

Technical Field

[0001] This invention belongs to the field of refractory alloy single crystal growth technology, specifically relating to an electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of molybdenum-rhenium alloy single crystals. Background Technology

[0002] In existing technologies, electron beam levitation melting is commonly used to prepare refractory metal single crystal materials. Although electron beam levitation melting can effectively prepare molybdenum-rhenium alloy single crystal materials, it is usually necessary to manufacture polycrystalline raw material rods for the preparation of refractory metal single crystals in order to obtain refractory metal single crystal rods with low impurity content and uniform and fine microstructure.

[0003] Furthermore, existing technologies typically employ powder mixing, sintering, melting, extrusion, and forging processes to prepare polycrystalline molybdenum-rhenium alloy rods. The melting stage usually requires at least two melting operations in an electron beam furnace to reduce the content of impurities such as C, H, O, and N. However, melting results in coarse ingot grains and a large ingot size. To reduce the ingot grain size and modify its dimensions, extrusion deformation, followed by forging and straightening, are necessary. These processes involve sawing away significant amounts of material, leading to a substantial decrease in raw material utilization, long process cycles, and extremely high manufacturing costs.

[0004] There are currently no reports on electron beam additive manufacturing of polycrystalline raw material rods for the preparation of molybdenum-rhenium alloy single crystals in the existing technology. Therefore, there is an urgent need to develop a method for electron beam additive manufacturing of polycrystalline raw material rods for the preparation of molybdenum-rhenium alloy single crystals. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing an electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of single crystals of molybdenum-rhenium alloy. This method directly spins and draws the rods after cold isostatic pressing and sintering, followed by electron beam additive manufacturing to print polycrystalline raw material rods of molybdenum-rhenium alloy. This avoids the multiple melting and subsequent extrusion processes required in the prior art, significantly improving raw material utilization and reducing manufacturing costs.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of molybdenum-rhenium alloy single crystals, characterized in that the method includes the following steps: Step 1: Mix molybdenum powder and rhenium powder to obtain a molybdenum-rhenium alloy mixed powder; Step 2: The molybdenum-rhenium alloy mixed powder obtained in Step 1 is loaded into a rubber sleeve, and then subjected to cold isostatic pressing to obtain molybdenum-rhenium alloy pressed rods. Step 3: Place the molybdenum-rhenium alloy pressed rods obtained in Step 2 into a sintering furnace for sintering to obtain sintered molybdenum-rhenium alloy rods; Step 4: The sintered rod of molybdenum-rhenium alloy obtained in Step 3 is rotary forged and then drawn into wire to obtain molybdenum-rhenium alloy wire. Step 5: The molybdenum-rhenium alloy wire obtained in Step 4 is subjected to alkaline washing, followed by ethanol cleaning, to obtain clean molybdenum-rhenium alloy wire. Step 6: Load the clean molybdenum-rhenium alloy wire obtained in Step 5 into the electron beam fused wire additive manufacturing equipment, and evacuate the vacuum. Control the printing height of the polycrystalline raw material rod by raising the electron beam focal height and raising the wire feeding height according to the set printing path. Perform electron beam fused wire additive manufacturing on the molybdenum substrate to obtain the molybdenum-rhenium alloy polycrystalline raw material rod. Step 7: The polycrystalline raw material rod of molybdenum-rhenium alloy obtained in Step 6 is turned or polished, then wiped clean with ethanol, and then used for electron beam levitation melting to prepare single crystal material of molybdenum-rhenium alloy.

[0007] This invention obtains molybdenum-rhenium alloy wire for preparing polycrystalline raw material rods of molybdenum-rhenium alloy by mixing molybdenum powder and rhenium powder, cold isostatic pressing, sintering, rotary forging, and drawing. The wire surface is cleaned with alkali and ethanol to remove oxides (such as MoO2 and MoO3), oil, and residual lubricant from the drawing process. The polycrystalline raw material rods of molybdenum-rhenium alloy are then obtained through electron beam fusion additive manufacturing. The obtained polycrystalline raw material rods of molybdenum-rhenium alloy can be directly used for electron beam levitation melting to prepare single crystal materials of molybdenum-rhenium alloy.

[0008] This invention modifies part of the process for preparing single-crystal molybdenum-rhenium alloy, specifically the preparation process for polycrystalline molybdenum-rhenium raw material rods. It uses molybdenum powder and rhenium powder to prepare molybdenum-rhenium alloy wire, which is then manufactured using electron beam fused wire additive manufacturing to obtain polycrystalline molybdenum-rhenium alloy raw material rods that meet the requirements for single-crystal growth. Additive manufacturing technology offers design flexibility, easily yielding rods of different diameters and lengths. Furthermore, the electron beam fused wire additive manufacturing process enables the melting and purification of the wire, reducing impurity content. Additionally, it eliminates the need for melting, extrusion, and forging processes in the production of polycrystalline molybdenum-rhenium alloy raw material rods, thereby significantly improving raw material utilization, reducing processing steps, and lowering overall processing costs. This solves the problems of excessively long processes and low raw material utilization in existing polycrystalline raw material rod preparation technologies.

[0009] The above-mentioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy is characterized in that the molybdenum powder and rhenium powder in step one have a mass purity of higher than 99.95% and a particle size of less than 10 μm. The mass fraction of rhenium powder in the mixed powder is 5%~25%, and the remainder is molybdenum powder. The mixing is carried out by using a V-type mixer at 30Hz~80Hz for 10h~20h. Because this invention first prepares polycrystalline molybdenum-rhenium alloy raw material rods, it has a wider range of applications. It can prepare polycrystalline molybdenum-rhenium alloy raw material rods with a rhenium mass fraction of 5% to 25%, resulting in a wider range of compositions. By controlling the purity of the raw materials and preventing the introduction of impurities during processing, the quality of the prepared polycrystalline molybdenum-rhenium alloy raw material rods is guaranteed. By controlling the particle size of molybdenum powder and rhenium powder, the uniform mixing of molybdenum powder and rhenium powder is guaranteed, while ensuring that the rods will not break during cold isostatic pressing. By controlling the mixing parameters, the thorough and uniform mixing of molybdenum powder and rhenium powder is guaranteed.

[0010] The above-mentioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy is characterized in that the diameter of the rubber sleeve in step two is 20mm~24mm, the peak static pressure load of the cold isostatic pressing is 180MPa~210MPa, and the holding time is 3min~8min. This invention, by controlling the diameter of the rubber sleeve, allows the obtained molybdenum-rhenium alloy sintered rods to be directly rotary forged without prior rapid forging, reducing the number of processes and the cost of the prepared wire. By controlling the cold isostatic pressing parameters, it ensures that the pressed rod is intact and does not break after cold isostatic pressing, preventing the rod from being unusable for wire drawing due to breakage.

[0011] The above-mentioned electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of single crystals of molybdenum-rhenium alloy is characterized in that the sintering furnace in step three is a hydrogen-protected sintering furnace, the sintering is carried out in a hydrogen atmosphere, the sintering temperature is 2000℃~2300℃, and the holding time is 3h~6h. This invention uses a hydrogen-protected sintering furnace to effectively reduce the oxygen content in the alloy, while simultaneously burning off oxygen in the environment, protecting the molybdenum-rhenium alloy from oxidation. By controlling the sintering parameters, sufficient sintering is ensured, resulting in sintered molybdenum-rhenium alloy rods with excellent performance.

[0012] The above-mentioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy is characterized in that the rotary forging in step four is carried out under hydrogen protection, and the wire drawing is carried out under a hydrogen atmosphere at a temperature of 800℃~1200℃, wherein the diameter of the molybdenum-rhenium alloy wire is 1.0mm~2.0mm. In this invention, rotary forging requires hydrogen protection, and the rotary forging furnace used is a hydrogen rotary forging furnace. The combustion of hydrogen provides the necessary temperature and simultaneously protects the molybdenum-rhenium alloy rod from oxidation by oxygen. This invention ensures the stability of the wire drawing process and prevents wire breakage by controlling the wire drawing parameters.

[0013] The above-described electron beam additive manufacturing method for preparing polycrystalline raw material rods of molybdenum-rhenium alloy single crystals is characterized in that, in step five, "cleanliness" refers to the surface of the molybdenum-rhenium alloy wire exhibiting a silvery-white color and metallic luster, with no impurities adhering to it. This invention, by controlling the surface quality of the molybdenum-rhenium alloy wire and preventing the introduction of impurities, ensures the quality of the prepared polycrystalline molybdenum-rhenium alloy raw material rods.

[0014] The above-mentioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy is characterized in that, in step six, the electron beam emitted by the thermionic gun of the electron beam fused wire additive manufacturing equipment bombards the molybdenum substrate, converting kinetic energy into thermal energy, thereby obtaining a molten pool, and then inserting clean molybdenum-rhenium alloy wire into the molten pool for melting and printing.

[0015] The above-mentioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy is characterized in that the vacuuming in step six is ​​at least 8.0 × 10⁻⁶. -2 Pa, the printing path is a circular printing route, and the diameter gradually increases from the inside to the outside. The diameter of the molybdenum-rhenium alloy polycrystalline raw material rod is 5mm~50mm, and the contents of C, H, O and N are all less than 80ppm. This invention prevents oxidation during electron beam fused wire additive manufacturing by controlling the vacuum level and rapidly removes impurities that volatilize or overflow from the molten pool during the process. Specifically, as the clean molybdenum-rhenium alloy wire is fully melted during electron beam fused wire additive manufacturing, impurities volatilize and are quickly removed using a vacuum system. This is because the melting point of molybdenum-rhenium alloy is extremely high, above 2600℃, facilitating the volatilization and removal of impurity elements. Furthermore, the small diameter of the alloy wire during electron beam fused wire additive manufacturing allows for more complete melting in the molten pool, providing sufficient time and space for impurities to volatilize. By employing a circular printing path with the diameter gradually increasing from the inside out, the diameter of the molybdenum-rhenium alloy polycrystalline raw material rods can be easily controlled. This invention allows for the production of molybdenum-rhenium alloy polycrystalline raw material rods with a wider diameter range through electron beam fused wire additive manufacturing, offering excellent designability and greater freedom, and is suitable for electron beam levitation region melting and purification or single crystal growth.

[0016] The aforementioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloys is characterized in that, in step six, raising the electron beam focus refers to raising the electron beam focus by 1mm to 3mm for each printed layer. The raising of the wire feed height is the same as raising the electron beam focus, and the two are adjusted in tandem. This invention raises the electron beam focus because the height of the rod increases after each printed layer, necessitating an increase in the electron gun height. The electron beam focus position is also the molten pool position, thus requiring a higher focus. Furthermore, the wire needs to be fed into the molten pool for melting; therefore, both the wire feed height and the focus height are constantly changing and must be coordinated.

[0017] The above-mentioned method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy is characterized in that, in step six, the electron beam voltage in the electron beam filament additive manufacturing is 47kV~53kV, the output current is 80mA~200mA, the wire feeding speed is 5mm / s~50mm / s, and the height of each additive layer is 0.8mm~3.2mm. This invention determines the output power by controlling the electron beam voltage and output current, ensuring a stable molten pool and stable melting of the wire fed into the molten pool without causing solidification or sudden enlargement of the molten pool, thus achieving smooth printing. By controlling the wire feeding speed, the growth rate of the rod is controlled, which, in conjunction with the output current of the electron beam, ensures smooth rod growth. By controlling the thickness of each additive layer, the uniformity of the preparation is ensured, thereby guaranteeing the quality of the polycrystalline raw material rods of molybdenum-rhenium alloy.

[0018] Compared with the prior art, the present invention has the following advantages: 1. This invention manufactures polycrystalline molybdenum-rhenium alloy rods by cold isostatic pressing, direct rotary forging and wire drawing after sintering, and subsequent electron beam additive manufacturing. It ingeniously achieves melting and impurity removal during printing, avoiding the multiple melting and subsequent extrusion processes required in existing technologies. This avoids expensive processing steps such as multiple melting and extrusion, and reduces the need for sawing the rods, thereby improving the utilization rate of raw materials and significantly reducing manufacturing costs. It solves the problems of extremely long manufacturing cycles, extremely low raw material utilization rates, and extremely high manufacturing costs of polycrystalline raw material rods used for the preparation of single crystals of molybdenum-rhenium alloy.

[0019] 2. This invention uses electron beam additive manufacturing to print polycrystalline raw material rods of molybdenum-rhenium alloy. This makes it easier to control the diameter and length of the rods, as they are not subject to the control of previous processes. In contrast, the dimensions of polycrystalline raw material rods prepared by existing technologies are heavily dependent on previous processes, making it difficult to control the dimensions of polycrystalline raw material rods. This invention replaces the existing raw material rod manufacturing technology in the preparation of single crystals of molybdenum-rhenium alloy.

[0020] 3. This invention uses electron beam additive manufacturing to print polycrystalline raw material rods for the preparation of molybdenum-rhenium alloy single crystals, which effectively reduces the content of impurities such as C, H, O and N. The content of impurities such as C, H, O and N inside the raw material rods prepared by existing technologies is comparable, but the cost is significantly reduced.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a macroscopic morphology diagram of the molybdenum-rhenium alloy polycrystalline raw material rod manufactured by electron beam fused wire additive manufacturing according to Embodiment 1 of the present invention. Detailed Implementation

[0023] Example 1 This embodiment includes the following steps: Step 1: Molybdenum powder and rhenium powder with a purity of 99.95% or higher are mixed in a V-type mixer at 50 Hz for 15 hours to obtain a molybdenum-rhenium alloy mixed powder; the mass fraction of rhenium powder in the mixed powder is 14%, and the remainder is molybdenum powder; Step 2: The molybdenum-rhenium alloy mixed powder obtained in Step 1 is loaded into a rubber sleeve with a diameter of 22mm, and then subjected to cold isostatic pressing to obtain a molybdenum-rhenium alloy pressed rod; the peak load of the cold isostatic pressing is 200MPa, and the holding time is 5min. Step 3: Place the molybdenum-rhenium alloy pressed rods obtained in Step 2 into a hydrogen-protected sintering furnace and heat to 2100℃ for sintering for 4.5 hours to obtain sintered molybdenum-rhenium alloy rods. Step 4: The sintered rod of molybdenum-rhenium alloy obtained in Step 3 is rotary forged under hydrogen protection, and then heated to 1000℃ in a hydrogen atmosphere for wire drawing to obtain molybdenum-rhenium alloy wire with a wire diameter of 1.5mm. Step 5: The molybdenum-rhenium alloy wire obtained in Step 4 is alkali-washed in sodium hydroxide solution and then cleaned with ethanol to obtain a clean molybdenum-rhenium alloy wire with a silvery-white surface and metallic luster, free of lubricating carbon and other impurities. Step Six: Load the clean molybdenum-rhenium alloy wire obtained in Step Five into an electron beam fused wire additive manufacturing equipment, and evacuate the vacuum to at least 8.0 × 10⁻⁶. -2Pa, on a molybdenum substrate, electron beam fused wire additive manufacturing of molybdenum-rhenium alloy polycrystalline raw material rods is carried out. Electrons emitted by the thermionic gun of the electron beam fused wire additive manufacturing equipment bombard the pure molybdenum substrate, converting kinetic energy into heat energy to obtain a molten pool. Then, clean molybdenum-rhenium alloy wires are inserted into the molten pool for melting and printing. By controlling the diameter of the circular printing path from the inside to the outside, the diameter of the raw material rod is controlled to be 25mm, and the printing substrate remains stationary. By coordinating the adjustment of raising the electron beam focus and the wire feeding height, the electron beam focus is raised by 1.4mm and the wire feeding height is raised by 1.4mm for each printed layer, so that the raw material rod grows along the height direction. By controlling the electron beam voltage to 50kV, the output current to 120mA, and the wire feeding speed to 20mm / s, the additive manufacturing layer thickness to be 1.2mm and the growth rate of the rod are controlled to obtain the molybdenum-rhenium alloy polycrystalline raw material rod. Step 7: The polycrystalline raw material rod of molybdenum-rhenium alloy obtained in Step 6 is turned or polished, then wiped clean with ethanol, and then used for electron beam levitation melting to prepare single crystal material of molybdenum-rhenium alloy.

[0024] Testing revealed that the mass fraction of oxygen in the polycrystalline raw material rods of molybdenum-rhenium alloy prepared in this embodiment was less than 0.005%, the mass fraction of hydrogen was less than 0.0005%, the mass fraction of hydrogen was less than 0.001%, and the mass fraction of carbon was less than 0.002%.

[0025] Figure 1 This is a macroscopic morphology image of the polycrystalline molybdenum-rhenium alloy rod manufactured by electron beam fused wire additive manufacturing in this embodiment. Figure 1 As can be seen from the figure, this embodiment successfully prepared polycrystalline raw material rods of molybdenum-rhenium alloy.

[0026] Example 2 This embodiment includes the following steps: Step 1: Molybdenum powder and rhenium powder with a purity of 99.95% or higher are mixed in a V-type mixer at 80 Hz for 10 hours to obtain a molybdenum-rhenium alloy mixed powder; the mass fraction of rhenium powder in the mixed powder is 5%, and the remainder is molybdenum powder; Step 2: The molybdenum-rhenium alloy mixed powder obtained in Step 1 is loaded into a rubber sleeve with a diameter of 24 mm, and then subjected to cold isostatic pressing to obtain a molybdenum-rhenium alloy pressed rod; the peak load of the cold isostatic pressing is 210 MPa, and the holding time is 3 min. Step 3: Place the molybdenum-rhenium alloy pressed rods obtained in Step 2 into a hydrogen-protected sintering furnace and heat to 2300℃ for sintering for 3 hours to obtain sintered molybdenum-rhenium alloy rods. Step 4: The sintered rod of molybdenum-rhenium alloy obtained in Step 3 is rotary forged under hydrogen protection, and then heated to 1200℃ in hydrogen atmosphere for wire drawing to obtain molybdenum-rhenium alloy wire with a wire diameter of 1.0 mm. Step 5: The molybdenum-rhenium alloy wire obtained in Step 4 is alkali-washed in sodium hydroxide solution and then cleaned with ethanol to obtain a clean molybdenum-rhenium alloy wire with a silvery-white surface and metallic luster, free of lubricating carbon and other impurities. Step Six: Load the clean molybdenum-rhenium alloy wire obtained in Step Five into an electron beam fused wire additive manufacturing equipment, and evacuate the vacuum to at least 8.0 × 10⁻⁶. -2 Pa, on a pure molybdenum substrate, electron beam fused wire additive manufacturing of molybdenum-rhenium alloy polycrystalline raw material rods is carried out. Electrons emitted by the thermionic gun of the electron beam fused wire additive manufacturing equipment bombard the pure molybdenum substrate, converting kinetic energy into heat energy to obtain a molten pool. Then, clean molybdenum-rhenium alloy wire is inserted into the molten pool for melting and printing. By controlling the diameter of the annular printing path from the inside to the outside, the diameter of the raw material rod is controlled to be 5mm, and the printing substrate remains stationary. By coordinating the adjustment of raising the electron beam focus and the wire feeding height, the electron beam focus is raised by 1mm and the wire feeding height is raised by 1mm for each printed layer, so that the raw material rod grows along the height direction. By controlling the electron beam voltage to 47kV, the output current to 80mA, and the wire feeding speed to 5mm / s, the additive manufacturing layer thickness to be 0.8mm and the growth rate of the rod are controlled to obtain the molybdenum-rhenium alloy polycrystalline raw material rod. Step 7: The polycrystalline raw material rod of molybdenum-rhenium alloy obtained in Step 6 is turned or polished, then wiped clean with ethanol, and then used for electron beam levitation melting to prepare single crystal material of molybdenum-rhenium alloy.

[0027] Testing revealed that the mass fraction of oxygen in the polycrystalline raw material rods of molybdenum-rhenium alloy prepared in this embodiment was less than 0.005%, the mass fraction of hydrogen was less than 0.0005%, the mass fraction of hydrogen was less than 0.001%, and the mass fraction of carbon was less than 0.002%.

[0028] Example 3 This embodiment includes the following steps: Step 1: Molybdenum powder and rhenium powder with a purity of 99.95% or higher are mixed in a V-type mixer at 30 Hz for 20 hours to obtain a molybdenum-rhenium alloy mixed powder; the mass fraction of rhenium powder in the mixed powder is 25%, and the remainder is molybdenum powder; Step 2: The molybdenum-rhenium alloy mixed powder obtained in Step 1 is loaded into a rubber sleeve with a diameter of 20 mm, and then subjected to cold isostatic pressing to obtain a molybdenum-rhenium alloy pressed rod; the peak load of the cold isostatic pressing is 180 MPa, and the holding time is 8 min. Step 3: Place the molybdenum-rhenium alloy pressed rods obtained in Step 2 into a hydrogen-protected sintering furnace and heat to 2000℃ for sintering for 6 hours to obtain sintered molybdenum-rhenium alloy rods. Step 4: The sintered rod of molybdenum-rhenium alloy obtained in Step 3 is rotary forged under hydrogen protection, and then heated to 800°C in a hydrogen atmosphere for wire drawing to obtain molybdenum-rhenium alloy wire with a diameter of 2.0 mm. Step 5: The molybdenum-rhenium alloy wire obtained in Step 4 is alkali-washed in sodium hydroxide solution and then cleaned with ethanol to obtain a clean molybdenum-rhenium alloy wire with a silvery-white surface and metallic luster, free of lubricating carbon and other impurities. Step Six: Load the clean molybdenum-rhenium alloy wire obtained in Step Five into an electron beam fused wire additive manufacturing equipment, and evacuate the vacuum to at least 8.0 × 10⁻⁶. -2 Pa, on a pure molybdenum substrate, electron beam fused wire additive manufacturing of molybdenum-rhenium alloy polycrystalline raw material rods is carried out. Electrons emitted by the thermionic gun of the electron beam fused wire additive manufacturing equipment bombard the pure molybdenum substrate, converting kinetic energy into heat energy to obtain a molten pool. Then, clean molybdenum-rhenium alloy wire is inserted into the molten pool for melting and printing. By controlling the diameter of the annular printing path from the inside to the outside, the diameter of the raw material rod is controlled to be 50 mm, and the printing substrate remains stationary. By coordinating the adjustment of raising the electron beam focus and the wire feeding height, the electron beam focus is raised by 3 mm and the wire feeding height is raised by 3 mm after each printing layer, so that the raw material rod grows along the height direction. By controlling the electron beam voltage to 53 kV, the electron beam output current to 200 mA, and the wire feeding speed to 50 mm / s, the additive manufacturing layer thickness to be 3.2 mm and the growth rate of the rod are controlled to obtain the molybdenum-rhenium alloy polycrystalline raw material rod. Step 7: The polycrystalline raw material rod of molybdenum-rhenium alloy obtained in Step 6 is turned or polished, then wiped clean with ethanol, and then used for electron beam levitation melting to prepare single crystal material of molybdenum-rhenium alloy.

[0029] Testing revealed that the mass fraction of oxygen in the polycrystalline raw material rods of molybdenum-rhenium alloy prepared in this embodiment was less than 0.005%, the mass fraction of hydrogen was less than 0.0005%, the mass fraction of hydrogen was less than 0.001%, and the mass fraction of carbon was less than 0.002%.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloys, characterized in that, The method includes the following steps: Step 1: Mix molybdenum powder and rhenium powder to obtain a molybdenum-rhenium alloy mixed powder; Step 2: The molybdenum-rhenium alloy mixed powder obtained in Step 1 is loaded into a rubber sleeve, and then subjected to cold isostatic pressing to obtain molybdenum-rhenium alloy pressed rods. Step 3: Place the molybdenum-rhenium alloy pressed rods obtained in Step 2 into a sintering furnace for sintering to obtain sintered molybdenum-rhenium alloy rods; Step 4: The sintered rod of molybdenum-rhenium alloy obtained in Step 3 is rotary forged and then drawn into wire to obtain molybdenum-rhenium alloy wire. Step 5: The molybdenum-rhenium alloy wire obtained in Step 4 is subjected to alkaline washing, followed by ethanol cleaning, to obtain clean molybdenum-rhenium alloy wire. Step Six: Load the clean molybdenum-rhenium alloy wire obtained in Step Five into an electron beam fused wire additive manufacturing equipment, and evacuate the vacuum. Following the set printing path, control the printing height of the polycrystalline raw material rod by increasing the electron beam focal height and the wire feeding height. Perform electron beam fused wire additive manufacturing on a molybdenum substrate to obtain a molybdenum-rhenium alloy polycrystalline raw material rod; the vacuum level is at least 8.0 × 10⁻⁶. -2 Pa, the printing path is a circular printing route, and the diameter gradually increases from the inside to the outside. The diameter of the molybdenum-rhenium alloy polycrystalline raw material rod is 5mm~50mm, and the content of C, H, O and N is all less than 80ppm. Raising the electron beam focus means raising the electron beam focus by 1mm~3mm for each printed layer. The raising the wire feeding height is the same as raising the electron beam focus, and the two are adjusted in coordination. In the electron beam filament additive manufacturing, the voltage of the electron beam is 47kV~53kV, the output current is 80mA~200mA, the wire feeding speed is 5mm / s~50mm / s, and the length and height of each additive layer are 0.8mm~3.2mm. Step 7: The polycrystalline raw material rod of molybdenum-rhenium alloy obtained in Step 6 is turned or polished, then wiped clean with ethanol, and then used for electron beam levitation melting to prepare single crystal material of molybdenum-rhenium alloy.

2. The method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy according to claim 1, characterized in that, In step one, the molybdenum powder and rhenium powder have a purity of over 99.95% and a particle size of less than 10 μm. The mass fraction of rhenium powder in the mixed powder is 5% to 25%, with the remainder being molybdenum powder. The mixing is carried out using a V-type mixer at 30 Hz to 80 Hz for 10 to 20 hours.

3. The electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of molybdenum-rhenium alloy single crystals according to claim 1, characterized in that, The diameter of the rubber sleeve in step two is 20mm~24mm, the peak static pressure load of the cold isostatic pressing is 180MPa~210MPa, and the holding time is 3min~8min.

4. The electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of molybdenum-rhenium alloy single crystals according to claim 1, characterized in that, The sintering furnace mentioned in step three is a hydrogen-protected sintering furnace. The sintering is carried out in a hydrogen atmosphere, the sintering temperature is 2000℃~2300℃, and the holding time is 3h~6h.

5. The method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy according to claim 1, characterized in that, The rotary forging in step four is carried out under hydrogen protection, the wire drawing is carried out under hydrogen atmosphere and heated to 800℃~1200℃, and the diameter of the molybdenum rhenium alloy wire is 1.0mm~2.0mm.

6. The method for electron beam additive manufacturing of polycrystalline raw material rods for preparing single crystals of molybdenum-rhenium alloy according to claim 1, characterized in that, The cleanliness mentioned in step five refers to the surface of the molybdenum-rhenium alloy wire exhibiting a silvery-white color and metallic luster, with no impurities adhering to it.

7. The electron beam additive manufacturing method for polycrystalline raw material rods used in the preparation of molybdenum-rhenium alloy single crystals according to claim 1, characterized in that, In step six, the electron beam fused wire additive manufacturing process uses electrons emitted from the thermionic gun of the electron beam fused wire additive manufacturing equipment to bombard the molybdenum substrate, converting kinetic energy into thermal energy to obtain a molten pool. Then, clean molybdenum-rhenium alloy wire is inserted into the molten pool for melting and printing.

Images