Preparation method of second-phase reinforced tungsten-rhenium alloy

Abstract

The invention is applicable to the technical field of alloy preparation, and provides a preparation method of a second-phase reinforced tungsten-rhenium alloy, which comprises the following steps: preparing a tungsten-rhenium precursor by a wet chemical method; carrying out spray drying operation on the prepared tungsten-rhenium precursor solution; reducing the prepared tungsten-rhenium precursor powder to obtain tungsten-rhenium alloy powder; and the obtained tungsten-rhenium alloy powder is subjected to SPS sintering, and a tungsten-rhenium alloy block is obtained. The influence of the second phase (ZrO2) on the microstructure and mechanical properties of the W-10wt% Re alloy is systematically explored by regulating and controlling the content of the second phase (ZrO2) and combining the SPS technology. Results show that along with the increase of the ZrO2 content, the powder refining degree is obviously improved, and the mechanical property of the alloy is correspondingly enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy preparation, and in particular to a method for preparing a second-phase reinforced tungsten-rhenium alloy. Background Art

[0002] CT (Computerized Tomography) has become an essential diagnostic tool in modern medicine. The performance of a CT machine depends largely on the quality of the X-ray tube. The anode target is a crucial component of the X-ray tube, directly affecting the X-ray emission intensity and tube life. When the X-ray tube is operating, the anode target is bombarded by a high-energy electron beam, emitting X-rays. However, the energy conversion efficiency is very low, only approximately 1%. Over 99% of the energy is converted into heat, with this heat primarily concentrated at the anode. In a vacuum environment, the temperature of the anode target can reach very high levels. It has been reported that the ambient temperature during X-ray tube operation is above 1300°C, with local temperatures reaching as high as 2600°C. Therefore, the material used for CT rotating anode targets requires high melting points, high heat capacity, low high-temperature vapor pressure, and excellent thermal shock resistance.

[0003] Tungsten has an extremely high elastic modulus (407 GPa at room temperature), a high melting point (3410°C), and high high-temperature strength. However, due to the intermittent operation of X-ray tubes, which alternate between hot and cold, the target surface material is prone to cracking. Tungsten is notch-sensitive, which can easily lead to crack propagation and deepening, leading to delamination from the substrate. This crack propagation and deepening exposes the substrate material to electron beam bombardment, generating X-rays of unwanted wavelengths and damaging the X-ray tube. To improve the overall performance of pure tungsten, a small amount of rhenium is added to tungsten. Rhenium and tungsten have similar atomic numbers and physical and chemical properties, making it easier to form an infinite solid solution. The addition of rhenium reduces the Peierls stress that causes plastic deformation of tungsten, thereby improving its plastic toughness. Due to the solid solution strengthening and toughening mechanisms caused by the addition of rhenium, tungsten as a target material significantly improves its resistance to electron bombardment, effectively reduces the dose decay rate, and reduces pure notch sensitivity, significantly extending the target's service life.

[0004] W-Re alloys are widely used as target materials in medical CT tubes. However, in actual operating conditions, W-Re targets are subject to severe thermal cycling, making them susceptible to cracking. This significantly reduces the target's service life and causes CT imaging artifacts, ultimately affecting image quality. Improving the performance of W-Re alloys by adding second-phase reinforcing particles to extend the life of CT tubes is a reasonable solution. ZrO2 is widely used to toughen other ceramics and brittle intermetallic compounds. Combining the excellent properties of ZrO2 and W-Re can effectively extend the service life and improve imaging quality. Conventional tungsten-rhenium alloy preparation involves compression molding followed by high-temperature sintering. However, due to the high-temperature, pressureless sintering performed in a protective atmosphere, the resulting tungsten-rhenium alloy has a low density. Furthermore, rapid diffusion at high temperatures results in coarse grains, resulting in poor hardness and strength. Spark plasma sintering (SPS), a novel technique for rapidly densifying tungsten-rhenium alloys, offers a fast heating rate, short sintering time, and high sintering density. By combining second-phase doping with SPS sintering, a superior second-phase doped W-Re alloy has been produced, extending the service life of medical CT scanners. Summary of the Invention

[0005] The present invention provides a preparation method of a second-phase reinforced tungsten-rhenium alloy to solve the technical problems mentioned in the background technology.

[0006] A method for preparing a second phase reinforced tungsten-rhenium alloy, the method comprising the following steps: S1. Preparation of tungsten-rhenium precursor by wet chemical method; S2, spray drying the tungsten-rhenium precursor solution prepared in step S1; S3, reducing the tungsten-rhenium precursor powder prepared in step S2 to obtain a tungsten-rhenium alloy powder; S4. Perform SPS sintering on the tungsten-rhenium alloy powder obtained in step S3 to obtain a tungsten-rhenium alloy block.

[0007] Preferably, in step S1, preparing the tungsten-rhenium precursor by a wet chemical method includes the following: First, add ammonium metatungstate powder into deionized water until it is fully dissolved, and place the solution in a magnetic stirrer and heat it at 60r / min to 100-120°C. After the temperature stabilizes, add ammonium rhenate to the solution. After the ammonium rhenate is fully stirred and dissolved, add different proportions of Zr(NO3)4·5H2O, and then add oxalic acid. After the oxalic acid is completely dissolved, stabilize the temperature at 100-120°C and let the solution react for 3-5h. After the solute reaction is complete, a tungsten-rhenium precursor solution is obtained, and the solid content of the precursor solution is 25%-32%.

[0008] Preferably, in step S1, the added amounts of ammonium rhenate, oxalic acid, and zirconium nitrate pentahydrate are 11.94%, 3.8%, and 0.57%-2.9% of the mass of ammonium metatungstate, respectively.

[0009] Preferably, in step S2, the step of spray drying the tungsten-rhenium precursor solution prepared in step S1 comprises: The experimental parameters of the spray drying equipment were set as follows: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350r / min, and feed rate 1-2L / h; the spray drying started heating and the inlet air temperature was raised to 200-230°C. After the outlet air temperature stabilized, the feed port and the tungsten-rhenium precursor solution were connected and the peristaltic pump was turned on. After the precursor solution was spray dried, the powder in the collection tank was collected to obtain tungsten-rhenium precursor powder.

[0010] Preferably, in step S3, the step of reducing the tungsten-rhenium precursor powder prepared in step S2 to obtain the tungsten-rhenium alloy powder comprises: Spread the tungsten-rhenium precursor powder in a firing boat, place the firing boat in a hydrogen reduction furnace, and then introduce hydrogen with a purity of ≥99.999% and a hydrogen flow rate of 2m 3 / h, ensure that there is no other gas in the tube furnace cavity except hydrogen, then heat it to 1000-1100℃ at 8-12℃ / min, keep it for 2-4h, then cool it to 480-520℃ at 8-12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0011] Preferably, in step S4, the step of performing SPS sintering on the tungsten-rhenium alloy powder obtained in step S3 to obtain a tungsten-rhenium alloy block includes: A graphite mold filled with tungsten-rhenium alloy powder was placed in a spark plasma sintering furnace chamber, a single-side axial pressure of 5 MPa was applied to the die, and the furnace chamber was vacuumed to 15 Pa; after sintering began, the sample was pre-loaded with 8 A current, and a current of 400 A was loaded at 700°C for 10 minutes to remove the gas adsorbed by the powder and the mold; the pressure was uniformly increased to 10 MPa, and when the furnace chamber pressure dropped back to 30 Pa, the current was continued to be loaded for sintering. The loading conditions were continued at a rate of 100 A / min until the maximum sintering temperature was reached, and then the temperature was increased at a rate of 150°C / min, while the pressure was uniformly increased to 50 MPa. When the temperature reached 1600°C, the heating was immediately stopped and cooled to room temperature with the furnace, and a tungsten-rhenium alloy block was obtained after sample removal.

[0012] Beneficial effects achieved by the present invention: This study systematically investigated the effect of controlling the second phase (ZrO2) content and combining it with SPS technology on the microstructure and mechanical properties of a W-10wt%Re alloy. Results show that increasing ZrO2 content significantly improves powder refinement and correspondingly enhances the alloy's mechanical properties. Leveraging the advantages of SPS's short sintering time and high density, a series of samples were successfully prepared. Comprehensive analysis confirmed that a 1wt% ZrO2 addition resulted in the alloy exhibiting optimal overall mechanical properties and minimum grain size, meeting industrial production requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Scanning electron microscope images of the precursors of Examples 1, 2, and 3.

[0014] Figure 2 The X-ray diffraction patterns of the reduced powders of Examples 1, 2, and 3 are shown.

[0015] Figure 3 Scanning electron microscope images of the sintered blocks of Examples 1, 2, and 3.

[0016] Figure 4 Statistical diagram of bulk grains after sintering of Examples 1, 2, and 3. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0018] Example 1, Step 1: Tungsten-Rhenium Precursor Ammonium metatungstate, ammonium rhenate, oxalic acid, and zirconium nitrate pentahydrate were dissolved in deionized water. First, ammonium metatungstate powder (AMT, Aladdin, purity ≥99.95%) was added to deionized water until fully dissolved. The mass ratio of ammonium metatungstate powder to deionized water was 1:4. The solution was heated in a magnetic stirrer with the rotor set to 60 rpm and the temperature raised to 120°C. After the temperature stabilized, ammonium rhenate (NH4ReO4, purity ≥99.9%) was added to the solution. After the ammonium rhenate was thoroughly stirred and dissolved, zirconium nitrate pentahydrate (Zr(NO3)4·5H2O) was added, followed by oxalic acid (C2H2O4·2H2O, analytical grade). After the oxalic acid was completely dissolved, the temperature was stabilized at 120°C and the solution was allowed to react for 5 hours. Once the solute reaction was complete, a tungsten-rhenium precursor solution with a solids content of 32% was obtained.

[0019] In step 1, the added amounts of ammonium rhenate, oxalic acid, and zirconium nitrate pentahydrate are 11.94%, 3.8%, and 0.57% of the mass of ammonium metatungstate, respectively.

[0020] Step 2: Spray drying to prepare the precursor The experimental parameters for the spray drying equipment were set to 230°C inlet air temperature, 100°C outlet air temperature, 350 r / min atomizer speed, and 1 L / h feed rate. The spray dryer began heating and raised the inlet air temperature to 230°C. After the outlet air temperature stabilized, the feed port was connected to the tungsten-rhenium precursor solution and the peristaltic pump was turned on. After the precursor solution was spray-dried, the powder was collected in a collection tank to obtain the tungsten-rhenium precursor powder.

[0021] Step 3: Restore The tungsten-rhenium precursor powder was spread evenly in the calcined boat, and then the calcined boat was placed in the hydrogen reduction furnace, and then hydrogen was introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h) to ensure that there is no gas other than hydrogen in the tube furnace cavity, then heat it to 1100℃ at 8℃ / min, keep it for 4h, then cool it to 480℃ at 12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0022] Step 4: SPS sintering A graphite mold filled with tungsten-rhenium alloy powder was placed in a spark plasma sintering furnace chamber, a single-side axial pressure of 5 MPa was applied to the die, and the furnace chamber was vacuumed to 15 Pa; after sintering began, the sample was pre-loaded with 8 A current, and a current of 400 A was loaded at 700°C for 10 minutes to remove the gas adsorbed by the powder and the mold; the pressure was uniformly increased to 10 MPa, and when the furnace chamber pressure dropped back to 30 Pa, the current was continued to be loaded for sintering. The loading conditions were continued at a rate of 100 A / min until the maximum sintering temperature was reached, and then the temperature was increased at a rate of 150°C / min, while the pressure was uniformly increased to 50 MPa. When the temperature reached 1600°C, the heating was immediately stopped and cooled to room temperature with the furnace, and a tungsten-rhenium alloy block was obtained after sample removal.

[0023] Example 2, Step 1: Tungsten-Rhenium Precursor First, ammonium metatungstate powder (AMT, Aladdin, purity ≥99.95%) is added to deionized water until fully dissolved. The mass ratio of ammonium metatungstate powder to deionized water is 1:4. The solution is then heated in a magnetic stirrer with the rotor adjusted to 60 rpm and the temperature raised to 120°C. After the temperature stabilizes, ammonium rhenate (NH4ReO4, purity ≥99.9%) is added to the solution. After the ammonium rhenate is fully stirred and dissolved, zirconium nitrate pentahydrate (Zr(NO3)4·5H2O) is added, followed by oxalic acid (C2H2O4·2H2O, analytical grade). After the oxalic acid is completely dissolved, the temperature is stabilized at 120°C and the solution is allowed to react for 5 hours. Once the solute reaction is complete, a tungsten-rhenium precursor solution with a solids content of 32% is obtained.

[0024] In step 1, the added amounts of ammonium rhenate, oxalic acid, and zirconium nitrate pentahydrate are 11.94%, 3.8%, and 1.4% of the mass of ammonium metatungstate, respectively.

[0025] Step 2: Spray drying to prepare the precursor The experimental parameters for the spray drying equipment were set to 230°C inlet air temperature, 100°C outlet air temperature, 350 r / min atomizer speed, and 1 L / h feed rate. The spray dryer began heating and raised the inlet air temperature to 230°C. After the outlet air temperature stabilized, the feed port was connected to the tungsten-rhenium precursor solution and the peristaltic pump was turned on. After the precursor solution was spray-dried, the powder was collected in a collection tank to obtain the tungsten-rhenium precursor powder.

[0026] Step 3: Restore The tungsten-rhenium precursor was spread flat in the firing boat, and then the firing boat was placed in the hydrogen reduction furnace, and then hydrogen was introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h) to ensure that there is no gas other than hydrogen in the tube furnace cavity, then heat it to 1100℃ at 8℃ / min, keep it for 4h, then cool it to 480℃ at 12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0027] Step 4: SPS sintering A graphite mold filled with tungsten-rhenium alloy powder was placed in a spark plasma sintering furnace chamber, a single-side axial pressure of 5 MPa was applied to the die, and the furnace chamber was vacuumed to 15 Pa; after sintering began, the sample was pre-loaded with 8 A current, and a current of 400 A was loaded at 700°C for 10 minutes to remove the gas adsorbed by the powder and the mold; the pressure was uniformly increased to 10 MPa, and when the furnace chamber pressure dropped back to 30 Pa, the current was continued to be loaded for sintering. The loading conditions were continued at a rate of 100 A / min until the maximum sintering temperature was reached, and then the temperature was increased at a rate of 150°C / min, while the pressure was uniformly increased to 50 MPa. When the temperature reached 1600°C, the heating was immediately stopped and cooled to room temperature with the furnace, and a tungsten-rhenium alloy block was obtained after sample removal.

[0028] Example 3, Step 1: Tungsten-Rhenium Precursor First, ammonium metatungstate powder (AMT, Aladdin, purity ≥99.95%) is added to deionized water until fully dissolved. The mass ratio of ammonium metatungstate powder to deionized water is 1:4. The solution is then heated in a magnetic stirrer with the rotor adjusted to 60 rpm and the temperature raised to 120°C. After the temperature stabilizes, ammonium rhenate (NH4ReO4, purity ≥99.9%) is added to the solution. After the ammonium rhenate is fully stirred and dissolved, zirconium nitrate pentahydrate (Zr(NO3)4·5H2O) is added, followed by oxalic acid (C2H2O4·2H2O, analytical grade). After the oxalic acid is completely dissolved, the temperature is stabilized at 120°C and the solution is allowed to react for 5 hours. Once the solute reaction is complete, a tungsten-rhenium precursor solution with a solids content of 32% is obtained.

[0029] In step 1, the added amounts of ammonium rhenate, oxalic acid, and zirconium nitrate pentahydrate are 11.94%, 3.8%, and 3.5% of the mass of ammonium metatungstate, respectively.

[0030] Step 2: Spray drying to prepare the precursor The experimental parameters for the spray drying equipment were set to 230°C inlet air temperature, 100°C outlet air temperature, 350 r / min atomizer speed, and 1 L / h feed rate. The spray dryer began heating and raised the inlet air temperature to 230°C. After the outlet air temperature stabilized, the feed port was connected to the tungsten-rhenium precursor solution and the peristaltic pump was turned on. After the precursor solution was spray-dried, the powder was collected in a collection tank to obtain the tungsten-rhenium precursor powder.

[0031] Step 3: Restore The tungsten-rhenium precursor was spread flat in the firing boat, and then the firing boat was placed in the hydrogen reduction furnace, and then hydrogen was introduced (hydrogen purity ≥ 99.999%, hydrogen flow rate 2m 3 / h) to ensure that there is no gas other than hydrogen in the tube furnace cavity, then heat it to 1100℃ at 8℃ / min, keep it for 4h, then cool it to 520℃ at 12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

[0032] Step 4: SPS sintering A graphite mold filled with tungsten-rhenium alloy powder was placed in a spark plasma sintering furnace chamber, a single-side axial pressure of 5 MPa was applied to the die, and the furnace chamber was vacuumed to 15 Pa; after sintering began, the sample was pre-loaded with 8 A current, and a current of 400 A was loaded at 700°C for 10 minutes to remove the gas adsorbed by the powder and the mold; the pressure was uniformly increased to 10 MPa, and when the furnace chamber pressure dropped back to 30 Pa, the current was continued to be loaded for sintering. The loading conditions were continued at a rate of 100 A / min until the maximum sintering temperature was reached, and then the temperature was increased at a rate of 150°C / min, while the pressure was uniformly increased to 50 MPa. When the temperature reached 1600°C, the heating was immediately stopped and cooled to room temperature with the furnace, and a tungsten-rhenium alloy block was obtained after sample removal.

[0033] The statistical results of the hardness of the sintered blocks of Examples 1, 2, and 3 are shown in Table 1.

[0034] Table 1 Hardness of blocks with different ZrO2 contents (unit / HV)

[0035] The present invention prepared W-10 (wt%) Re-xZrO2 powder by wet chemical method to obtain the second phase reinforced W-Re alloy. The powder was subjected to SPS sintering to obtain Examples 1 to 3. The precursor powder SEM showed ( Figure 1 ), as the precursor powder agglomerates with the increase of the second phase content, a certain agglomeration phenomenon begins to appear. Then the reduced powder was analyzed by XRD ( Figure 2 ), no ZrO2 peak was found because the amount of second phase added was small, only 1% at most, which is a normal phenomenon. However, it was observed that the diffraction peaks of the reduced tungsten-rhenium alloy powder shifted to higher angles relative to the W powder. According to the Bragg equation 2dsinθ=nλ, the addition of Re reduces the interplanar spacing. As the interplanar spacing decreases, the plastic toughness and hardness of the material will be improved. Subsequently, the fracture morphology and grain statistics of the SPS sintered samples were analyzed ( Figure 3 and Figure 4 ), Figure 3Figure ac shows the fracture morphology of tungsten-rhenium alloys with ZrO2 contents of 0.2%, 0.5%, and 1% at a magnification of 3000 times, while figure df shows the fracture morphology at a magnification of 10,000 times. It was observed that the average particle size of the tungsten-rhenium alloy with a ZrO2 content of 0.2% was 0.8 μm, the average particle size of the tungsten-rhenium alloy with a ZrO2 content of 0.5% was 0.66 μm, and the average particle size of the tungsten-rhenium alloy with a ZrO2 content of 1% was 0.54 μm. The particle size distribution results further demonstrate that the addition of ZrO2 has a grain refinement effect, and the grain refinement effect increases with increasing ZrO2 content. With the addition of the second phase ZrO2, the grains are refined. Since smaller grains lead to more grain boundaries, dislocation motion is hindered, and the macroscopic manifestation is an increase in strength. The hardness of the block was then measured. The hardness measurement results are shown in Table 1. Clearly, the block hardness increases with increasing ZrO2 content. The present invention determines the optimal content of ZrO2 by changing the addition amount of ZrO2 combined with SPS sintering, and the prepared samples can meet the needs of actual production.

[0036] It should be noted that, in this document, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a second phase enhanced tungsten-rhenium alloy, characterized in that: The preparation method comprises the following steps: S1. Preparation of tungsten-rhenium precursor by wet chemical method; S2, spray drying the tungsten-rhenium precursor solution prepared in step S1; S3, reducing the tungsten-rhenium precursor powder prepared in step S2 to obtain a tungsten-rhenium alloy powder; S4, performing SPS sintering on the tungsten-rhenium alloy powder obtained in step S3 to obtain a tungsten-rhenium alloy block; In step S1, the wet chemical method for preparing the tungsten-rhenium precursor includes the following: First, add ammonium metatungstate powder into deionized water until it is fully dissolved, and place the solution in a magnetic stirrer for heating. Adjust the rotor to 60r / min and raise the temperature to 100-120°C. After the temperature stabilizes, add ammonium rhenate to the solution. After the ammonium rhenate is fully stirred and dissolved, add different proportions of Zr(NO3)4·5H2O, and then add oxalic acid. After the oxalic acid is completely dissolved, stabilize the temperature at 100-120°C and let the solution react for 3-5h. After the solute reaction is complete, a tungsten-rhenium precursor solution is obtained. The solid content of the precursor solution is 25%-32%.

2. The method for preparing a second phase enhanced tungsten-rhenium alloy according to claim 1, wherein: In step S1 , the added amounts of ammonium rhenate, oxalic acid, and zirconium nitrate pentahydrate are 11.94%, 3.8%, and 0.57%-2.9% of the mass of ammonium metatungstate, respectively.

3. The method for preparing a second phase enhanced tungsten-rhenium alloy according to claim 1, characterized in that: In step S2, the step of spray drying the tungsten-rhenium precursor solution prepared in step S1 includes: The experimental parameters of the spray drying equipment were set as follows: inlet air temperature 200-230°C, outlet air temperature 100-120°C, atomizer speed 300-350r / min, and feed rate 1-2L / h; the spray drying started heating and the inlet air temperature was raised to 200-230°C. After the outlet air temperature stabilized, the feed port and the tungsten-rhenium precursor solution were connected and the peristaltic pump was turned on. After the precursor solution was spray dried, the powder in the collection tank was collected to obtain tungsten-rhenium precursor powder.

4. The method for preparing a second phase enhanced tungsten-rhenium alloy according to claim 1, characterized in that: In step S3, the tungsten-rhenium precursor powder prepared in step S2 is reduced to obtain tungsten-rhenium alloy powder, comprising: Spread the tungsten-rhenium precursor powder in a firing boat, place the firing boat in a hydrogen reduction furnace, and then introduce hydrogen with a purity of ≥99.999% and a hydrogen flow rate of 2m 3 / h, ensure that there is no other gas in the tube furnace cavity except hydrogen, then heat it to 1000-1100℃ at 8-12℃ / min, keep it for 2-4h, then cool it to 480-520℃ at 8-12℃ / min, and then cool it to room temperature with the furnace to obtain tungsten-rhenium alloy powder.

5. The method for preparing a second phase enhanced tungsten-rhenium alloy according to claim 1, characterized in that: In step S4, the tungsten-rhenium alloy powder obtained in step S3 is subjected to SPS sintering to obtain a tungsten-rhenium alloy block, which includes: A graphite mold filled with tungsten-rhenium alloy powder is placed in a spark plasma sintering furnace chamber, a single-sided axial pressure of 5 MPa is applied to the die, and the furnace chamber is vacuumed to 15 Pa; after sintering begins, the sample is pre-loaded with 8 A current, and a current of 400 A is loaded at 500-800 ° C for 10 minutes to remove the gas adsorbed by the powder and the mold; the pressure is uniformly increased to 10 MPa, and when the furnace chamber pressure drops back to 30 Pa, the current is continued to be loaded for sintering. The loading conditions are continued at a rate of 100 A / min until the maximum sintering temperature is reached, and then the temperature is increased at a rate of 150 ° C / min, while the pressure is uniformly increased to 50 MPa. When the temperature reaches 1600 ° C, the heating is immediately stopped and cooled to room temperature with the furnace. After removing the sample, a tungsten-rhenium alloy block is obtained.

Images