A high-performance tungsten-rhenium alloy and its preparation method

Abstract

The present invention relates to the field of alloy preparation technology, and discloses a method for preparing a high-performance tungsten-rhenium alloy, comprising the following steps: Step 1: Preparation of tungsten-rhenium alloy powder, dissolving a certain proportion of ammonium metatungstate, ammonium rhenate, and oxalic acid in deionized water, and placing the solution in a magnetic stirrer for heating to 100-120°C. The solution is allowed to react for 3-5 hours, and the solid content of the precursor solution is 25%-32%. Precursor powder is then prepared using a spray drying device, and the spray drying parameters are set: inlet air temperature of 200-230°C, outlet air temperature of 100-120°C, atomizer speed of 300-350r / min, and feed rate of 1-2L / h. The tungsten-rhenium precursor is then hydrogen reduced, the tungsten-rhenium precursor is spread flat in a calcined boat, the calcined boat is then placed in a hydrogen reduction furnace, the hydrogen reduction furnace is vacuumed, and hydrogen is then introduced. The preparation method proposed in the present invention can prepare a single-phase tungsten-rhenium alloy with good solid solubility, high high-temperature strength, high hardness, high density and certain ductility.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy preparation, in particular to a high-performance tungsten-rhenium alloy and a preparation method thereof. Background Art

[0002] As a novel solid-phase joining technology, friction stir welding (FSW) has been widely used due to its advantages such as energy saving and environmental protection, low heat input, small weld deformation, high welding precision and high welding quality. The stirring head is the most critical and most prone to failure in the friction stir welding process. It mainly consists of a clamping handle, a shoulder and a stirring needle. The stirring needle penetrates deep into the welded material and is subjected to strong friction wear and high-temperature cyclic stress. Therefore, the stirring needle material is required to be high-temperature resistant, have excellent creep resistance, high hardness, good thermal fatigue resistance and a certain degree of plasticity and toughness. The development of high-performance stirring needle materials will greatly expand the scope of application of FSW.

[0003] Metal tungsten has an extremely high elastic modulus (407GPa at room temperature) and a high melting point (3380℃), so it can be used as an ideal high-strength and heat-resistant material for friction stir welding stirring tips. Pure tungsten has a high ductile-brittle transition temperature (>500℃), so it is very easy to fail due to brittle fracture below 500℃. At the same time, pure tungsten will undergo recrystallization behavior above 1200℃, causing high-temperature brittleness, so its practical application is often limited. Rhenium and tungsten are adjacent in the periodic table and have similar physical and chemical properties and atomic structures. They can form a tungsten-rhenium alloy with good solid solubility and trigger the "rhenium effect" to produce a solid solution softening effect. The solid solution of high rhenium content not only increases the hardness and strength of tungsten, but also significantly improves the plasticity and toughness of tungsten. Therefore, tungsten-rhenium alloy can be used as an ideal material for friction stir welding stirring needles.

[0004] Currently, most methods for preparing tungsten-rhenium alloy powders use mechanical alloying. However, mechanical alloying relies on applied stress to achieve solid solution formation, requiring lengthy ball milling processes and easily introducing impurities. Furthermore, the milled tungsten-rhenium alloy powders exhibit significant residual stress, leading to rapid grain growth during subsequent sintering. Furthermore, high-energy ball milling is an energy-intensive and time-consuming powder preparation process, making it difficult to scale up for industrial production. In contrast, wet chemical methods produce tungsten-rhenium alloy powders with uniform composition distribution, are simple, rapid, and cost-effective, making them suitable for industrial production.

[0005] Conventional tungsten-rhenium alloy preparation is achieved by compression molding followed by high-temperature sintering. However, since the sintering is performed at high temperature and without pressure in a protective atmosphere, the density of the tungsten-rhenium alloy obtained by this sintering method is not high, and the tungsten-rhenium alloy diffuses rapidly at high temperatures, resulting in coarse grains. As a result, the hardness and strength of the tungsten-rhenium alloy obtained by compression sintering are poor. Spark plasma sintering (SPS), as a new technology for rapidly densifying tungsten-rhenium alloys, has the characteristics of fast heating rate, short sintering time, and high sintering density. However, due to the closed nature of the mold and the short sintering time, it is easy to cause problems such as excessive oxygen content in the material, low grain boundary strength, and low solid solubility of the tungsten-rhenium alloy, resulting in the material exhibiting disadvantages such as high brittleness and low strength. The invention uses a wet chemical method and adds oxalic acid as a process control agent to prepare a tungsten-rhenium precursor powder with uniform composition distribution, then reduces the precursor powder with hydrogen to obtain a tungsten-rhenium alloy powder with good solid solubility, then uses high-temperature hydrogen sintering to prepare a tungsten-rhenium alloy block, and finally uses high-temperature rolling technology to prepare a high-hardness, high-density, ultra-high-strength single-phase W-25 (wt%) Re alloy with uniform composition. Summary of the Invention

[0006] In order to solve the problems raised in the background technology, the present invention provides a high-performance tungsten-rhenium alloy and a preparation method thereof.

[0007] The present invention is achieved by adopting the following technical solutions:

[0008] A method for preparing a high-performance tungsten-rhenium alloy comprises the following steps:

[0009] Step 1: Preparation of tungsten-rhenium alloy powder

[0010] A certain proportion of ammonium metatungstate (AMT, Aladdin, purity ≥99.95%), ammonium rhenate (NH4ReO4, purity ≥99.9%), and oxalic acid (C2H2O4·2H2O, analytical grade) were dissolved in deionized water. The solution was heated in a magnetic stirrer to 100-120°C. The solution was allowed to react for 3-5 hours, and the solid content of the precursor solution was 25%-32%. The precursor powder was then prepared using a spray dryer with the following spray drying parameters: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350 r / min, and feed rate 1-2 L / h. Then, the tungsten-rhenium precursor is reduced with hydrogen. The tungsten-rhenium precursor is spread flat in a firing boat, and the firing boat is placed in a hydrogen reduction furnace. The hydrogen reduction furnace is evacuated and then hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h), then raise the temperature to 1000-1100℃ at 8-12℃ / min, keep it for 2-4h, then reduce the temperature to 480-520℃ at 8-12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0011] In step 1, the added amounts of ammonium rhenate and oxalic acid are 35.79% and 26.49% of the mass of ammonium metatungstate, respectively.

[0012] Step 2: High temperature hydrogen sintering

[0013] Place the mold filled with tungsten-rhenium alloy powder in a tablet press, apply a single-side axial pressure of 650-700 MPa to the die, and maintain the pressure for 1-2 minutes, then release the pressure and take out the pressed block. Pre-sinter the pressed block in hydrogen, spread the block flat in a sintering boat, and then place the sintering boat in a hydrogen sintering furnace. Vacuum the hydrogen sintering furnace and then introduce hydrogen (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h), then heat up to 1300-1400℃ at 8-12℃ / min, keep warm for 1-2h, then cool down to 480-520℃ at 8-12℃ / min, then cool to room temperature with the furnace to obtain a tungsten-rhenium alloy with a certain bonding strength. Finally, the pre-sintered block is subjected to high-temperature hydrogen sintering, and the sintering boat with the block is placed in the medium frequency furnace, and then hydrogen is introduced (hydrogen purity ≥99.999%, hydrogen flow rate 8m 3 / h), then heat up to 2100-2200℃ at 10-15℃ / min, keep warm for 2-4h, reduce the temperature to 580-620℃ at 10-15℃ / min, and then cool to room temperature with the furnace to obtain tungsten-rhenium alloy.

[0014] Step 3: Rolling process

[0015] The tungsten-rhenium alloy block obtained by high temperature sintering is placed in a tube furnace and hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 5m 3 The block is then heated at a rate of 15-20°C / min to 1150-1250°C, held at that temperature for 0.5-1h, and quickly placed in a YZ-60-310-2 rolling mill for high-temperature rolling with a deformation of 10-15%. Subsequently, high-temperature rolling is performed at 1200°C with deformations of 8-10%, 6-8%, 4-6%, and 2-4%, respectively. After rolling, the surface oxide layer is removed with a grinding wheel to obtain a tungsten-rhenium alloy block.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention utilizes a wet chemical method and changes the environment of a precursor solution by adding oxalic acid as a process control agent, so that the oxalic acid fully reacts with ammonium metatungstate and ammonium rhenate, thereby improving the performance of the precursor powder, which is beneficial to improving the composition uniformity of the tungsten-rhenium alloy powder after hydrogen reduction and the pre-alloying process. Then, a tungsten-rhenium alloy block is prepared by high-temperature hydrogen sintering. On the one hand, the long high-temperature holding time allows the tungsten and rhenium elements to fully diffuse and dissolve, so that the "rhenium effect" is fully exerted in the tungsten matrix, thereby improving the ductility of the tungsten-rhenium alloy.

[0018] The present invention adopts hydrogen reduction to effectively remove residual oxygen impurities in tungsten-rhenium alloy powder, avoids impurity enrichment at grain boundaries, and thus increases the grain boundary strength of the tungsten-rhenium alloy. Finally, by changing the rolling deformation of the tungsten-rhenium alloy in the high-temperature rolling technology, and thus changing the microstructure such as dislocation density, grain size and orientation, and grain boundary strength, a single-phase tungsten-rhenium alloy with good solid solubility, high high-temperature strength, high hardness, high density and certain ductility is finally prepared. The tungsten-rhenium alloy after high-temperature rolling has a relative density of 99.2%, a microhardness of 630±10Hv, and an ultimate tensile strength of 1345MPa at 300°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Scanning electron microscope images of tungsten-rhenium alloy powder. (a) and (b) are the SEM morphologies of tungsten-rhenium alloy powder prepared by wet method at different magnifications.

[0020] Figure 2 The tungsten-rhenium alloy blocks obtained in Examples 1, 2, 3, and 4, (a), (b), (c), and (d) are tungsten-rhenium alloy blocks in the sintered state, with a rolling deformation of 30%, a rolling deformation of 40%, and a rolling deformation of 50%, respectively;

[0021] Figure 3 The microhardness and relative density line graph of the tungsten-rhenium alloy obtained in Examples 1, 2, and 3

[0022] Figure 4 Scanning electron micrographs of the tungsten-rhenium alloy surfaces obtained in Examples 1, 2, and 3; (a) is the SEM morphology of the WRE surface; (b) and (c) are the SEM morphologies of the R30-WRE and R40-WRE surfaces along the RD / ND direction, respectively.

[0023] Figure 5 Scanning electron micrographs of the tensile fracture surfaces of the tungsten-rhenium alloys obtained in Examples 1, 2, and 3; (a) is the SEM morphology of the WRE fracture surface; (b) and (c) are the SEM morphologies of the R30-WRE and R40-WRE fracture surfaces, respectively.

[0024] Figure 6The tensile engineering stress-engineering strain curves of the tungsten-rhenium alloy obtained in Examples 1, 2, and 3 are shown; and the tensile engineering stress-engineering strain curves of WRE, R30-WRE, and R40-WRE at 300°C are shown.

[0025] Figure 7 This is the X-ray diffraction pattern of the tungsten-rhenium alloy obtained in Example 3. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0027] Example 1

[0028] A tungsten-rhenium alloy and a preparation method thereof, comprising the following steps

[0029] Step 1: Preparation of tungsten-rhenium alloy powder

[0030] A certain proportion of ammonium metatungstate (AMT, Aladdin, purity ≥99.95%), ammonium rhenate (NH4ReO4, purity ≥99.9%), and oxalic acid (C2H2O4·2H2O, analytical grade) were dissolved in deionized water. The solution was heated in a magnetic stirrer to 100-120°C. The solution was allowed to react for 3-5 hours, and the solid content of the precursor solution was 25%-32%. The precursor powder was then prepared using a spray dryer with the following spray drying parameters: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350 r / min, and feed rate 1-2 L / h. The tungsten-rhenium precursor is then reduced with hydrogen, the tungsten-rhenium precursor is spread flat in a firing boat, the firing boat is then placed in a hydrogen reduction furnace, the hydrogen reduction furnace is evacuated and hydrogen is then introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate is 2m3 / h), the temperature is then raised to 1000-1100°C at 8-12°C / min, kept warm for 2-4h, and then lowered to 480-520°C at 8-12°C / min, and then cooled to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0031] In step 1, the added amounts of ammonium rhenate and oxalic acid are 35.79% and 26.49% of the mass of ammonium metatungstate, respectively.

[0032] Step 2: High temperature hydrogen sintering

[0033] The mold containing the tungsten-rhenium alloy powder is placed in a tablet press. A single-sided axial pressure of 650-700 MPa is applied to the die and maintained for 1-2 minutes. The pressure is then released and the pressed block is removed. The pressed block is hydrogen pre-sintered and the block is spread flat in a sintering boat. The sintering boat is then placed in a hydrogen sintering furnace. The hydrogen sintering furnace is evacuated and then hydrogen (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m3 / h) is introduced. The temperature is then raised to 1300-1400°C at 8-12°C / min, held for 1-2 hours, then cooled to 480-520°C at 8-12°C / min, and then cooled to room temperature with the furnace to obtain a tungsten-rhenium alloy with a certain bonding strength. Finally, the pre-sintered blocks are subjected to high-temperature hydrogen sintering, and the sintering boat with the blocks is placed in a medium-frequency furnace. Subsequently, hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate is 8m3 / h), and then the temperature is raised to 2100-2200℃ at 10-15℃ / min, kept warm for 2-4h, and then reduced to 580-620℃ at 10-15℃ / min, and then cooled to room temperature with the furnace to obtain tungsten-rhenium alloy.

[0034] The alloy block obtained in this embodiment is a tungsten-rhenium alloy (WRE) that has been sintered in high-temperature hydrogen and is not rolled.

[0035] Example 2

[0036] A tungsten-rhenium alloy and a preparation method thereof, comprising the following steps

[0037] Step 1: Preparation of tungsten-rhenium alloy powder

[0038] A certain proportion of ammonium metatungstate (AMT, Aladdin, purity ≥99.95%), ammonium rhenate (NH4ReO4, purity ≥99.9%), and oxalic acid (C2H2O4·2H2O, analytical grade) were dissolved in deionized water. The solution was heated in a magnetic stirrer to 100-120°C. The solution was allowed to react for 3-5 hours, and the solid content of the precursor solution was 25%-32%. The precursor powder was then prepared using a spray dryer with the following spray drying parameters: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350 r / min, and feed rate 1-2 L / h. The tungsten-rhenium precursor is then reduced with hydrogen, the tungsten-rhenium precursor is spread flat in a firing boat, the firing boat is then placed in a hydrogen reduction furnace, the hydrogen reduction furnace is evacuated and hydrogen is then introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate is 2m3 / h), the temperature is then raised to 1000-1100°C at 8-12°C / min, kept warm for 2-4h, and then lowered to 480-520°C at 8-12°C / min, and then cooled to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0039] In step 1, the added amounts of ammonium rhenate and oxalic acid are 35.79% and 26.49% of the mass of ammonium metatungstate, respectively.

[0040] Step 2: High temperature hydrogen sintering

[0041] The mold containing the tungsten-rhenium alloy powder is placed in a tablet press. A single-sided axial pressure of 650-700 MPa is applied to the die and maintained for 1-2 minutes. The pressure is then released and the pressed block is removed. The pressed block is hydrogen pre-sintered and the block is spread flat in a sintering boat. The sintering boat is then placed in a hydrogen sintering furnace. The hydrogen sintering furnace is evacuated and then hydrogen (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m3 / h) is introduced. The temperature is then raised to 1300-1400°C at 8-12°C / min, held for 1-2 hours, then cooled to 480-520°C at 8-12°C / min, and then cooled to room temperature with the furnace to obtain a tungsten-rhenium alloy with a certain bonding strength. Finally, the pre-sintered blocks are subjected to high-temperature hydrogen sintering, and the sintering boat with the blocks is placed in a medium-frequency furnace. Subsequently, hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate is 8m3 / h), and then the temperature is raised to 2100-2200℃ at 10-15℃ / min, kept warm for 2-4h, and then reduced to 580-620℃ at 10-15℃ / min, and then cooled to room temperature with the furnace to obtain tungsten-rhenium alloy.

[0042] Step 3: Rolling process

[0043] The tungsten-rhenium alloy block obtained by high-temperature sintering is placed in a tubular furnace and hydrogen (hydrogen purity ≥ 99.999%, hydrogen flow rate 5m3 / h) is introduced. The temperature is then raised to 1150-1250°C at a rate of 15-20°C / min and held at that temperature for 0.5-1h. The block is then quickly placed in a YZ-60-310-2 rolling mill for high-temperature rolling with a rolling deformation of 10%. Subsequently, high-temperature rolling is performed at 1200°C with deformations of 8%, 6%, 4%, and 2%, respectively. After rolling, the surface oxide layer is removed with a grinding wheel to obtain a tungsten-rhenium alloy block.

[0044] The alloy block obtained in this embodiment is a tungsten-rhenium alloy (R30-WRE) that has been subjected to high-temperature hydrogen sintering and high-temperature rolling (total rolling deformation of 30%).

[0045] Example 3

[0046] A tungsten-rhenium alloy and a preparation method thereof, comprising the following steps

[0047] Step 1: Preparation of tungsten-rhenium alloy powder

[0048] A certain proportion of ammonium metatungstate (AMT, Aladdin, purity ≥99.95%), ammonium rhenate (NH4ReO4, purity ≥99.9%), and oxalic acid (C2H2O4·2H2O, analytical grade) were dissolved in deionized water. The solution was heated in a magnetic stirrer to 100-120°C. The solution was allowed to react for 3-5 hours, and the solid content of the precursor solution was 25%-32%. The precursor powder was then prepared using a spray dryer with the following spray drying parameters: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350 r / min, and feed rate 1-2 L / h. The tungsten-rhenium precursor is then reduced with hydrogen, the tungsten-rhenium precursor is spread flat in a firing boat, the firing boat is then placed in a hydrogen reduction furnace, the hydrogen reduction furnace is evacuated and hydrogen is then introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate is 2m3 / h), the temperature is then raised to 1000-1100°C at 8-12°C / min, kept warm for 2-4h, and then lowered to 480-520°C at 8-12°C / min, and then cooled to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0049] In step 1, the added amounts of ammonium rhenate and oxalic acid are 35.79% and 26.49% of the mass of ammonium metatungstate, respectively.

[0050] Step 2: High temperature hydrogen sintering

[0051] The mold containing the tungsten-rhenium alloy powder is placed in a tablet press. A single-sided axial pressure of 650-700 MPa is applied to the die and maintained for 1-2 minutes. The pressure is then released and the pressed block is removed. The pressed block is hydrogen pre-sintered and the block is spread flat in a sintering boat. The sintering boat is then placed in a hydrogen sintering furnace. The hydrogen sintering furnace is evacuated and then hydrogen (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m3 / h) is introduced. The temperature is then raised to 1300-1400°C at 8-12°C / min, held for 1-2 hours, then cooled to 480-520°C at 8-12°C / min, and then cooled to room temperature with the furnace to obtain a tungsten-rhenium alloy with a certain bonding strength. Finally, the pre-sintered blocks are subjected to high-temperature hydrogen sintering, and the sintering boat with the blocks is placed in a medium-frequency furnace. Subsequently, hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate is 8m3 / h), and then the temperature is raised to 2100-2200℃ at 10-15℃ / min, kept warm for 2-4h, and then reduced to 580-620℃ at 10-15℃ / min, and then cooled to room temperature with the furnace to obtain tungsten-rhenium alloy.

[0052] Step 3: Rolling process

[0053] The tungsten-rhenium alloy block obtained by high temperature sintering is placed in a tube furnace and hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 5m 3The block is then heated at a rate of 15-20°C / min to 1150-1250°C, held at that temperature for 0.5-1h, and quickly placed on a YZ-60-310-2 rolling mill for high-temperature rolling with a 12% deformation. Subsequently, high-temperature rolling is performed at 1200°C with deformations of 10%, 8%, 6%, and 4%, respectively. After rolling, the surface oxide layer is removed with a grinding wheel to obtain a tungsten-rhenium alloy block.

[0054] The alloy block obtained in this embodiment is a tungsten-rhenium alloy (R40-WRE) that has been subjected to high-temperature hydrogen sintering and high-temperature rolling (total rolling deformation of 40%).

[0055] Example 4

[0056] A tungsten-rhenium alloy and a preparation method thereof, comprising the following steps

[0057] Step 1: Preparation of tungsten-rhenium alloy powder

[0058] A certain proportion of ammonium metatungstate (AMT, Aladdin, purity ≥99.95%), ammonium rhenate (NH4ReO4, purity ≥99.9%), and oxalic acid (C2H2O4·2H2O, analytical grade) were dissolved in deionized water. The solution was heated in a magnetic stirrer to 100-120°C. The solution was allowed to react for 3-5 hours, and the solid content of the precursor solution was 25%-32%. The precursor powder was then prepared using a spray dryer with the following spray drying parameters: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350 r / min, and feed rate 1-2 L / h. Then, the tungsten-rhenium precursor is reduced with hydrogen. The tungsten-rhenium precursor is spread flat in a firing boat, and the firing boat is placed in a hydrogen reduction furnace. The hydrogen reduction furnace is evacuated and then hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h), then raise the temperature to 1000-1100℃ at 8-12℃ / min, keep it for 2-4h, then reduce the temperature to 480-520℃ at 8-12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0059] In step 1, the added amounts of ammonium rhenate and oxalic acid are 35.79% and 26.49% of the mass of ammonium metatungstate, respectively.

[0060] Step 2: High temperature hydrogen sintering

[0061] Place the mold filled with tungsten-rhenium alloy powder in a tablet press, apply a single-side axial pressure of 650-700 MPa to the die, and maintain the pressure for 1-2 minutes, then release the pressure and take out the pressed block. Pre-sinter the pressed block in hydrogen, spread the block flat in a sintering boat, and then place the sintering boat in a hydrogen sintering furnace. Vacuum the hydrogen sintering furnace and then introduce hydrogen (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h), then heat up to 1300-1400℃ at 8-12℃ / min, keep warm for 1-2h, then cool down to 480-520℃ at 8-12℃ / min, then cool to room temperature with the furnace to obtain a tungsten-rhenium alloy with a certain bonding strength. Finally, the pre-sintered block is subjected to high-temperature hydrogen sintering, and the sintering boat with the block is placed in the medium frequency furnace, and then hydrogen is introduced (hydrogen purity ≥99.999%, hydrogen flow rate 8m 3 / h), then heat up to 2100-2200℃ at 10-15℃ / min, keep warm for 2-4h, reduce the temperature to 580-620℃ at 10-15℃ / min, and then cool to room temperature with the furnace to obtain tungsten-rhenium alloy.

[0062] Step 3: Rolling process

[0063] The tungsten-rhenium alloy block obtained by high temperature sintering is placed in a tube furnace and hydrogen is introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 5m 3 The block is then heated at a rate of 15-20°C / min to 1150-1250°C, held at that temperature for 0.5-1h, and quickly placed on a YZ-60-310-2 rolling mill for high-temperature rolling with a deformation of 14%. Subsequently, high-temperature rolling is performed at 1200°C with deformations of 12%, 10%, 8%, and 6%, respectively. After rolling, the surface oxide layer is removed with a grinding wheel to obtain a tungsten-rhenium alloy block.

[0064] The alloy block obtained in this embodiment is a tungsten-rhenium alloy (R50-WRE) that has been subjected to high-temperature hydrogen sintering and high-temperature rolling (total rolling deformation of 50%).

[0065] Among them, WRE, R30-WRE, R40-WRE and R50-WRE are tungsten-rhenium alloys with unrolled, 30% rolling total deformation, 40% rolling total deformation and 50% rolling total deformation respectively.

[0066] From the above results, it can be seen that the tungsten-rhenium alloy powder prepared by wet chemical method and adding oxalic acid as process control agent shows excellent performance after high temperature hydrogen sintering and high temperature rolling. Figure 2 、 3As shown in the figure, within the appropriate range, the relative density and microhardness of the tungsten-rhenium alloy gradually increase with the increase of the total rolling deformation. When the total rolling deformation is 50%, the sample cracks. Compared with the tungsten-rhenium alloy sintered in high-temperature hydrogen, its relative density and microhardness increase by 41.4‰ and 43.2% respectively after rolling, and can reach up to 99.2% and 630±10Hv. Figure 4 As shown in the figure, the sintered tungsten-rhenium alloy is equiaxed and has many voids, with an average grain size of 26μm, while the R40-WRE surface is dense and the grains are obviously refined, with an average grain size of only 17μm. Figure 5 、 6 As shown in the figure, the strength and ductility of the tungsten-rhenium alloy are greatly improved after rolling. The ultimate tensile strength at 300℃ can reach 1345MPa and the elongation can reach 4%. From the fracture analysis, the entire fracture process of R40-WRE is dominated by transgranular fracture and ductile fracture of deformed structure, while the sintered state is dominated by intergranular fracture and transgranular dissociation fracture. This phenomenon is due to the increase in dislocation density, grain refinement and enhanced grain boundary strength of the tungsten-rhenium alloy caused by high-temperature rolling. Figure 7 XRD patterns show that after prolonged high-temperature hydrogen sintering and high-temperature rolling, the tungsten and rhenium elements diffuse evenly and form a tungsten-rhenium alloy with good solid solubility. This invention utilizes a wet chemical method with the addition of oxalic acid as a process control agent to prepare the tungsten-rhenium alloy powder. By modifying the high-temperature hydrogen sintering and high-temperature rolling processes, the performance of the tungsten-rhenium alloy is further improved, resulting in a single-phase tungsten-rhenium alloy with high high-temperature strength, high hardness, high density, and a certain degree of ductility and good solid solubility.

[0067] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a high-performance tungsten-rhenium alloy, characterized in that: The steps include: Step 1: Preparation of tungsten-rhenium alloy powder Dissolve ammonium metatungstate, ammonium rhenate, and oxalic acid in deionized water respectively, and place the solution in a magnetic stirrer for heating to 100-120°C. Allow the solution to react for 3-5 hours, and the solid content of the precursor solution is 25%-32%. Then, use a spray drying device to prepare a precursor powder. Then, hydrogen is reduced on the tungsten-rhenium precursor, and the tungsten-rhenium precursor is spread flat on a calcined boat. The calcined boat is then placed in a hydrogen reduction furnace, which is vacuumed and then hydrogen is introduced. The temperature is then raised to 1000-1100°C at 8-12°C / min, kept at this temperature for 2-4 hours, and then reduced to 480-520°C at 8-12°C / min. The tungsten-rhenium alloy powder is then obtained by cooling the furnace to room temperature. Step 2: High temperature hydrogen sintering The mold filled with tungsten-rhenium alloy powder is placed in a tablet press, and a single-side axial pressure of 650-700 MPa is applied to the die, and the pressure is maintained for 1-2 minutes. Then the pressure is released and the pressed block is taken out. The pressed block is hydrogen pre-sintered, and the block is spread flat in a sintering boat. The sintering boat is then placed in a hydrogen sintering furnace. The hydrogen sintering furnace is vacuumed and then hydrogen is introduced. The temperature is then raised to 1300-1400°C at 8-12°C / min, kept warm for 1-2 hours, and then heated to 1500-1800°C. The temperature is reduced to 480-520℃ at 8-12℃ / min, and then cooled to room temperature with the furnace to obtain a tungsten-rhenium alloy with a certain bonding strength. Finally, the pre-sintered block is subjected to high-temperature hydrogen sintering. The sintering boat with the block is placed in a medium-frequency furnace, and then hydrogen is introduced. The temperature is then increased to 2100-2200℃ at 10-15℃ / min, kept warm for 2-4h, and reduced to 580-620℃ at 10-15℃ / min. Then, the tungsten-rhenium alloy is obtained by cooling to room temperature with the furnace. Step 3: Rolling process The tungsten-rhenium alloy block obtained by high-temperature sintering is placed in a tubular furnace and hydrogen is introduced. The temperature is then raised to 1150-1250°C at a rate of 15-20°C / min and kept warm for 0.5-1h. The block is then quickly placed in a YZ-60-310-2 rolling mill for high-temperature rolling with a rolling deformation of 10-15%. Subsequently, high-temperature rolling is performed at 1200°C with deformations of 8-10%, 6-8%, 4-6%, and 2-4%, respectively. After rolling, the surface oxide layer is removed with a grinding wheel to obtain a tungsten-rhenium alloy block.

2. A high performance tungsten-rhenium alloy and a preparation method thereof according to claim 1, characterized in that: In the step 1, the spray drying parameters are set as follows: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350 r / min, and feed rate 1-2 L / h.

3. The method for preparing a high-performance tungsten-rhenium alloy according to claim 1, wherein: In step 1, the addition amounts of ammonium rhenate and oxalic acid are 35.79% and 26.49% of the mass of ammonium metatungstate, respectively.

4. The method for preparing a high-performance tungsten-rhenium alloy according to claim 1, wherein: In the step 1, the purity of hydrogen is ≥99.999%, and the hydrogen flow rate is 2 m³ / h.

5. The method for preparing a high-performance tungsten-rhenium alloy according to claim 1, wherein: In the step 2, the purity of the hydrogen after vacuum treatment is ≥99.999%, and the hydrogen flow rate is 2 m³ / h; the purity of the hydrogen introduced into the intermediate frequency furnace is ≥99.999%, and the hydrogen flow rate is 8 m³ / h.

6. The method for preparing a high-performance tungsten-rhenium alloy according to claim 1, wherein: In step 3, the purity of hydrogen is ≥99.999%, and the hydrogen flow rate is 5m³ / h.

7. A high-performance tungsten-rhenium alloy, prepared by the method for preparing a high-performance tungsten-rhenium alloy according to any one of claims 1 to 6.

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