Nb-W-V-HfN alloy and preparation method thereof
By introducing V and HfN elements into the Nb-W alloy matrix, optimizing the alloy composition, and using a specific process flow to prepare Nb-W-V-HfN alloy, solving the shortcomings in strength and plasticity of the existing Nb alloys and achieving high temperature While the tensile strength is similar to that of Nb521, the elongation is significantly improved.
Patent Information
- Application Number
- CN202411547052.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-01
- Publication Date
- 2025-02-11
AI Technical Summary
There is still room for improvement in strength and plasticity of existing Nb alloys, especially the problem of low elongation under high temperature conditions.
By introducing V and HfN elements into the Nb-W alloy matrix, the composition ratio of W and HfN in the alloy is optimized, and Nb-W-V-HfN alloy is prepared by using processes such as electronic balance weighing, arc furnace smelting and vacuum annealing.
The room temperature mechanical properties of Nb-W-V-HfN alloy are achieved, and the high-temperature tensile strength is similar to that of Nb521, and the elongation is significantly improved to 35%.
Smart Images
Figure CN119410986A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of structural materials, and in particular relates to a Nb-WV-HfN ultrahigh temperature alloy and a preparation method thereof. Technical Background
[0002] Niobium alloys are widely used in key aerospace components such as rocket nozzles and jet aircraft thermal transformers due to their high melting point, high specific strength, and good room temperature processing and welding properties. With the rapid iterative development of my country's aerospace technology, the requirements for material properties are becoming more and more stringent. The existing process is to add W, Mo, Zr, Hf and other elements to the Nb matrix, and through the solid solution elements and the precipitation of dispersed second phase particles, the movement of dislocations is effectively hindered, thereby improving the strength of the Nb alloy. However, the strength of the Nb alloy obtained in this way still needs to be improved, and the plasticity is relatively low.
[0003] In view of the above problems, the present invention provides a method with excellent room temperature mechanical properties, high temperature strength similar to that of the new generation Nb521 alloy, but improved elongation. Summary of the invention
[0004] The purpose of the present invention is to provide a method for preparing a Nb-WV-HfN alloy, thereby improving the excellent room temperature mechanical properties and high temperature elongation of the alloy.
[0005] A Nb-WV-HfN alloy, characterized in that it comprises the following substances: niobium Nb, tungsten W, vanadium V and hafnium nitride HfN, with the mass percentages of 7% to 10% W powder, 2% to 2.7% V sheets, 0.3% to 0.7% HfN powder, and the balance being Nb particles and inevitable impurities.
[0006] Preferably, the mass percentages are 8% to 10% of W powder, 2% to 2.4% of V flakes, 0.4% to 0.6% of HfN powder, and the remainder is Nb particles and unavoidable impurities.
[0007] The preferred mass percentages are 9% to 10% W powder, 2% to 2.3% V flakes, 0.5% to 0.6% HfN powder, and the remainder is Nb particles and inevitable impurities.
[0008] Using the mass percentage of each element of the above Nb-WV-HfN alloy, a method for preparing a Nb-WV-HfN alloy is prepared, which is characterized by comprising the following steps:
[0009] Step 1, using an electronic balance to weigh the mass percentage of each element of a Nb-WV-HfN alloy with a purity greater than 99.95% according to claims 1-3, weighing Nb particles, W powder, V sheets and HfN powder together, and then mixing them evenly to obtain a raw material for preparing the Nb alloy;
[0010] Step 2: Use 20% hydrochloric acid and ethanol to clean the water-cooled copper crucible to avoid the influence of residual impurity elements;
[0011] Step 3: Place the mixed raw materials in a water-cooled copper crucible in the electric arc furnace, ensure that the exhaust valve is closed and tighten the furnace door; use a mechanical pump to evacuate the furnace until the pressure in the furnace chamber drops below 5Pa, and then turn off the mechanical pump; then slowly introduce argon to 0.05-0.055MPa, and then close the argon valve; start the mechanical pump again to evacuate until the chamber pressure reaches below 4Pa, then raise the gate valve; when the pressure in the chamber no longer rises and reaches 4Pa, turn on the molecular pump; use the molecular pump to further pump the pressure in the furnace chamber to 4×10 -3 Pa, then close the gate valve and molecular pump, and re-introduce argon until the pressure in the furnace cavity reaches 0.05MPa; finally, turn on the arc furnace power supply for smelting; after the molecular pump speed drops to 0, close the diffusion valve and mechanical pump;
[0012] Step 4: Place the tungsten needle 3mm above the titanium block in a vacuum arc furnace, and then use a current of 300A to melt the upper and lower surfaces of the titanium block to absorb the residual oxygen in the cavity. At the same time, the air tightness of the furnace can be judged according to the color change of the titanium block. After the titanium block is smelted, move the tungsten needle to 3mm above the raw material. During the first round of smelting, use a low current of 200A to fuse the raw materials into a block to avoid powder splashing during subsequent smelting. Increase the current to 400A, and continue to melt the raw materials on the upper and lower sides for 6 times. During the last smelting, reduce the current to 250A and continue to melt the upper and lower surfaces of the sample. At the end of smelting, quickly turn off the current to avoid undulations on the sample surface. After the sample is smelted, let the sample stand for 20 minutes. Then use a mechanical pump to pump the pressure in the furnace to less than 10MPa. Open the exhaust valve, open the furnace door when the pressure inside and outside the cavity is consistent, use a spray bottle to spray ethanol on the surface of the sample to cool it, and finally take a sample to obtain a silver-white disc-shaped niobium alloy block.
[0013] Step 5: Place the niobium alloy block in a vacuum annealing furnace and use a mechanical pump and a diffusion pump furnace to pump the pressure in the furnace to 4×10 -3Pa, heating from room temperature to 1550℃~1650℃ at a heating rate of 9~10℃ / min, keeping the temperature for 4 hours, and cooling with the furnace to obtain an annealed Nb alloy block; placing the Nb block obtained after annealing in a muffle furnace at 450℃~480℃ for 10 minutes, taking out the sample, and rolling the sample using a rolling mill; during the rolling process, the roller descends by 0.20mm~0.24mm at a time, and after a single rolling, the sample needs to be placed in a muffle furnace for 40s~50s, and the rolling is terminated when the sample thickness is reduced to about 0.15mm; the rolled sample is placed in a vacuum annealing furnace again, and a mechanical pump and a diffusion pump are used to make the pressure in the furnace reach 4×10 -3 Pa, heated from room temperature to 1350°C-1450°C at a heating rate of 9-10°C / min, kept at that temperature for more than 1 hour, and cooled in the furnace to obtain the final Nb alloy sample.
[0014] Compared with the prior art, the present invention has the following beneficial effects:
[0015] 1. Experiments have proved that the tensile strengths of Nb10W2V0.69HfN (10% W, 2% V, 0.69% HfN, and the rest is Nb) and Nb7.5W2V0.69HfN (7.5% W, 2% V, 0.69% HfN, and the rest is Nb) are 670MPa and 581MPa respectively, and the room temperature elongations are 11% and 29% respectively; in the 1550-1650℃ tensile test, the elongations of the two are 35% and 29% respectively, which are better than the 17% elongation of Nb521 when stretched at 1550-1650℃.
[0016] Second, V and HfN are introduced into the matrix of Nb-W alloy to increase the room temperature strength of the alloy to 581-670 MPa, and by optimizing the composition ratio of W and HfN in the alloy, the room temperature elongation of the alloy can be close to 30%.
[0017] Fourth, V and HfN are introduced into the matrix of Nb-W alloy, and the tensile strength at 1550-1650℃ is close to that of Nb521, while the elongation at 1550-1650℃ is increased to 35%. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 , is the room temperature tensile curve of Nb10W2V0.69HfN alloy. It can be seen from the figure that the room temperature tensile strength of the alloy is 670MPa and the elongation is 11%.
[0019] Figure 2 , is the tensile mechanical property curve of Nb10W2V0.69HfN alloy at 1550-1650℃. It can be seen from the figure that the tensile strength of the alloy at 1550-1650℃ is 98MPa, and the elongation reaches 35%. DETAILED DESCRIPTION
[0020] In order to achieve the above object, the technical solution adopted by the present invention is:
[0021] Nb-WV-HfN alloy is made by adding V element to the Nb-W alloy matrix, and adding a small amount of HfN to improve its room temperature strength and high temperature strength. The tensile strength of Nb10W2V0.69HfN and Nb7.5W2V0.69HfN are 670MPa and 581MPa respectively, and the room temperature elongation is 11% and 29% respectively; in the 1550-1650℃ tensile test, the elongation of the two is 35% and 29% respectively, which is better than the 17% elongation of Nb521 when stretched at 1550-1650℃.
[0022] Implementation Case 1:
[0023] Step 1: Use an electronic balance to weigh Nb particles with a purity greater than 99.95% and a mass fraction of 87.66%, 10% W powder, 2% V sheets, and 0.34% HfN powder, and then evenly mix them to obtain a raw material for preparing the Nb alloy.
[0024] Step 2: Use 20% hydrochloric acid and ethanol to clean the copper crucible to avoid the influence of residual impurity elements. Then place the mixed raw materials in a water-cooled copper crucible in the electric arc furnace, make sure the exhaust valve is closed and tighten the furnace door. Use a mechanical pump to vacuum the furnace until the pressure in the furnace chamber drops to 5Pa, then turn off the mechanical pump. Then slowly introduce argon to 0.05MPa, and then close the argon valve. Start the mechanical pump again to vacuum until the chamber pressure reaches 4Pa, then raise the gate valve. When the pressure in the chamber no longer rises and reaches 4Pa, turn on the molecular pump. Use the molecular pump to further pump the pressure in the furnace chamber to 4×10 -3 Pa, then close the gate valve and molecular pump, re-introduce argon gas to the furnace cavity pressure of 0.05MPa, and finally turn on the arc furnace power supply for smelting. After the molecular pump speed drops to 0, close the diffusion valve and mechanical pump.
[0025] Step 3: Place the tungsten needle 3mm above the titanium block, and then use a current of 300A to melt the upper and lower surfaces of the titanium block to absorb the residual oxygen in the cavity. At the same time, the air tightness of the furnace can be judged by the color change of the titanium block. After the titanium block is melted, move the tungsten needle to 3mm above the raw material. During the first round of melting, use a low current of 200A to fuse the raw materials into a block to avoid powder splashing during subsequent melting. Increase the current to 400A and continue to melt the raw materials on the upper and lower sides for 6 times. For the last melting, reduce the current to 250A and continue to melt the upper and lower surfaces of the sample. Turn off the current quickly at the end of melting to avoid undulations on the sample surface. After the sample is melted, let the sample stand for 20 minutes. Then use a mechanical pump to pump the pressure in the furnace to less than 10MPa. Open the exhaust valve, open the furnace door when the pressure inside and outside the cavity is consistent, use a spray pot to spray ethanol on the surface of the sample to cool it, and finally take a sample to obtain a silver-white disc-shaped niobium alloy block.
[0026] Step 4: Place the niobium alloy block in a vacuum annealing furnace and use a mechanical pump and a diffusion pump furnace to pump the pressure in the furnace to 4×10 -3 Pa, heated from room temperature to 1550-1650℃ at a heating rate of 9-10℃ / min, kept warm for 4 hours, and cooled in the furnace to obtain an annealed Nb alloy block. After the annealed Nb block was placed in a muffle furnace at 450-460℃ for 10 minutes, the sample was taken out and rolled using a rolling mill. During the rolling process, the roller dropped 0.24mm at a time. After a single rolling, the sample was placed in a muffle furnace for 40 seconds. When the sample thickness dropped to about 0.15mm, the rolling was terminated. The rolled sample was placed back in a vacuum annealing furnace, and a mechanical pump and a diffusion pump were used to make the pressure in the furnace reach 4×10 -3 After Pa, the sample was heated from room temperature to 1350-1450°C at a heating rate of 9-10°C / min, kept at that temperature for 1 hour, and then cooled in the furnace to obtain the final Nb alloy sample.
[0027] Implementation Case 2:
[0028] Step 1: Use an electronic balance to weigh Nb particles with a purity greater than 99.95% and a mass fraction of 87.31%, 10% W powder, 2% V sheets, and 0.69% HfN powder, and then evenly mix them to obtain a raw material for preparing a Nb alloy.
[0029] Step 2: Use 20% hydrochloric acid and ethanol to clean the copper crucible to avoid the influence of residual impurity elements. Then place the mixed raw materials in a water-cooled copper crucible in the electric arc furnace, make sure the exhaust valve is closed and tighten the furnace door. Use a mechanical pump to vacuum the furnace until the pressure in the furnace chamber drops to 5Pa, then turn off the mechanical pump. Then slowly introduce argon to 0.03MPa, and then close the argon valve. Start the mechanical pump again to vacuum until the chamber pressure reaches 4Pa, then raise the gate valve. When the pressure in the chamber no longer rises and reaches 4Pa, turn on the molecular pump. Use the molecular pump to further pump the pressure in the furnace chamber to 4×10 -3 Pa, then close the gate valve and molecular pump, re-introduce argon gas to the furnace cavity pressure of 0.05MPa, and finally turn on the arc furnace power supply for smelting. After the molecular pump speed drops to 0, close the diffusion valve and mechanical pump.
[0030] Step 3: Place the tungsten needle 3mm above the titanium block, and then use a current of 300A to melt the upper and lower surfaces of the titanium block to absorb the residual oxygen in the cavity. At the same time, the air tightness of the furnace can be judged by the color change of the titanium block. After the titanium block is melted, move the tungsten needle to 3mm above the raw material. During the first round of melting, use a low current of 200A to fuse the raw materials into a block to avoid powder splashing during subsequent melting. Increase the current to 400A and continue to melt the raw materials on the upper and lower sides for 6 times. For the last melting, reduce the current to 250A and continue to melt the upper and lower surfaces of the sample. Turn off the current quickly at the end of melting to avoid undulations on the sample surface. After the sample is melted, let the sample stand for 20 minutes. Then use a mechanical pump to pump the pressure in the furnace to less than 10MPa. Open the exhaust valve, open the furnace door when the pressure inside and outside the cavity is consistent, use a spray pot to spray ethanol on the surface of the sample to cool it, and finally take a sample to obtain a silver-white disc-shaped niobium alloy block.
[0031] Step 4: Place the niobium alloy block in a vacuum annealing furnace and use a mechanical pump and a diffusion pump furnace to pump the pressure in the furnace to 4×10 -3 After Pa, the temperature was increased from room temperature to 1550-1650℃ at a heating rate of 9-10℃ / min, and the temperature was kept at 1550-1650℃ for 4 hours, and the annealed Nb alloy block was obtained by furnace cooling. The Nb block obtained after annealing was placed in a muffle furnace at 450-460℃ for 10 minutes, then the sample was taken out and rolled using a rolling mill. During the rolling process, the roller dropped 0.32mm at a time. After a single rolling, the sample was placed in a muffle furnace for 40 seconds. When the sample thickness was reduced to about 0.15mm, the rolling was terminated. The rolled sample was placed back in a vacuum annealing furnace, and a mechanical pump and a diffusion pump were used to make the pressure in the furnace reach 4×10 -3 After Pa, the sample was heated from room temperature to 1350-1450°C at a heating rate of 9-10°C / min, kept at that temperature for 1 hour, and then cooled in the furnace to obtain the final Nb alloy sample.
[0032] Implementation Case 3:
[0033] Step 1: Use an electronic balance to weigh Nb particles with a purity greater than 99.95% and a mass fraction of 89.81%, 7.5% W powder, 2% V sheets, and 0.69% HfN powder, and then evenly mix them to obtain a raw material for preparing the Nb alloy.
[0034] Step 2: Use 20% hydrochloric acid and ethanol to clean the copper crucible to avoid the influence of residual impurity elements. Then place the mixed raw materials in a water-cooled copper crucible in the electric arc furnace, make sure the exhaust valve is closed and tighten the furnace door. Use a mechanical pump to vacuum the furnace until the pressure in the furnace chamber drops to 5Pa, then turn off the mechanical pump. Then slowly introduce argon to 0.03MPa, and then close the argon valve. Start the mechanical pump again to vacuum until the chamber pressure reaches 4Pa, then raise the gate valve. When the pressure in the chamber no longer rises and reaches 4Pa, turn on the molecular pump. Use the molecular pump to further pump the pressure in the furnace chamber to 4×10 -3 Pa, then close the gate valve and molecular pump, re-introduce argon gas to the furnace cavity pressure of 0.05MPa, and finally turn on the arc furnace power supply for smelting. After the molecular pump speed drops to 0, close the diffusion valve and mechanical pump.
[0035] Step 3: Place the tungsten needle 3mm above the titanium block, and then use a current of 300A to melt the upper and lower surfaces of the titanium block to absorb the residual oxygen in the cavity. At the same time, the air tightness of the furnace can be judged by the color change of the titanium block. After the titanium block is melted, move the tungsten needle to 3mm above the raw material. During the first round of melting, use a low current of 200A to fuse the raw materials into a block to avoid powder splashing during subsequent melting. Increase the current to 400A and continue to melt the raw materials on the upper and lower sides for 6 times. For the last melting, reduce the current to 250A and continue to melt the upper and lower surfaces of the sample. Turn off the current quickly at the end of melting to avoid undulations on the sample surface. After the sample is melted, let the sample stand for 20 minutes. Then use a mechanical pump to pump the pressure in the furnace to less than 10MPa. Open the exhaust valve, open the furnace door when the pressure inside and outside the cavity is consistent, use a spray pot to spray ethanol on the surface of the sample to cool it, and finally take a sample to obtain a silver-white disc-shaped niobium alloy block.
[0036] Step 4: Place the niobium alloy block in a vacuum annealing furnace and use a mechanical pump and a diffusion pump furnace to pump the pressure in the furnace to 4×10 -3Pa, heated from room temperature to 1550-1650℃ at a heating rate of 9-10℃ / min, kept warm for 4 hours, and cooled in the furnace to obtain an annealed Nb alloy block. After the annealed Nb block was placed in a muffle furnace at 450-460℃ for 10 minutes, the sample was taken out and rolled using a rolling mill. During the rolling process, the roller dropped 0.24mm at a time. After a single rolling, the sample was placed in a muffle furnace for 40 seconds. When the sample thickness dropped to about 0.15mm, the rolling was terminated. The rolled sample was placed back in a vacuum annealing furnace, and a mechanical pump and a diffusion pump were used to make the pressure in the furnace reach 4×10 -3 After Pa, the sample was heated from room temperature to 1350-1450°C at a heating rate of 9-10°C / min, kept at that temperature for 1 hour, and then cooled in the furnace to obtain the final Nb alloy sample.
Claims
1. A Nb-WV-HfN alloy, characterized in that: It comprises the following substances: niobium Nb, tungsten W, vanadium V and hafnium nitride HfN, with the mass percentages of 7% to 10% of W powder, 2% to 2.7% of V sheets, 0.3% to 0.7% of HfN powder, and the balance of Nb particles and inevitable impurities.
2. A Nb-WV-HfN alloy according to claim 1, characterized in that: The mass percentages are 8% to 10% of W powder, 2% to 2.4% of V sheets, 0.4% to 0.6% of HfN powder, and the remainder is Nb particles and inevitable impurities.
3. The Nb-WV-HfN alloy according to claim 1, characterized in that: The mass percentages are 9% to 10% of W powder, 2% to 2.3% of V sheets, 0.5% to 0.6% of HfN powder, and the remainder is Nb particles and inevitable impurities.
4. A method for preparing a Nb-WV-HfN alloy by using the mass percentage of each element of the Nb-WV-HfN alloy according to claims 1 to 3, characterized in that: The following steps are involved: Step 1, using an electronic balance to weigh the mass percentage of each element of a Nb-WV-HfN alloy with a purity greater than 99.95% according to claims 1-3, weighing Nb particles, W powder, V sheets and HfN powder together, and then mixing them evenly to obtain a raw material for preparing the Nb alloy; Step 2: Use 20% hydrochloric acid and ethanol to clean the water-cooled copper crucible to avoid the influence of residual impurity elements; Step 3: Place the mixed raw materials in a water-cooled copper crucible in the electric arc furnace, ensure that the exhaust valve is closed and tighten the furnace door; use a mechanical pump to evacuate the furnace until the pressure in the furnace chamber drops below 5Pa, and then turn off the mechanical pump; then slowly introduce argon to 0.05-0.055MPa, and then close the argon valve; start the mechanical pump again to evacuate until the chamber pressure reaches below 4Pa, then raise the gate valve; when the pressure in the chamber no longer rises and reaches 4Pa, turn on the molecular pump; use the molecular pump to further pump the pressure in the furnace chamber to 4×10 -3 Pa, then close the gate valve and molecular pump, and re-introduce argon until the pressure in the furnace cavity reaches 0.05MPa; finally, turn on the arc furnace power supply for smelting; after the molecular pump speed drops to 0, close the diffusion valve and mechanical pump; Step 4: Place the tungsten needle 3mm above the titanium block in a vacuum arc furnace, and then use a current of 300A to melt the upper and lower surfaces of the titanium block to absorb the residual oxygen in the cavity. At the same time, the air tightness of the furnace can be judged according to the color change of the titanium block. After the titanium block is smelted, move the tungsten needle to 3mm above the raw material. During the first round of smelting, use a low current of 200A to fuse the raw materials into a block to avoid powder splashing during subsequent smelting. Increase the current to 400A, and continue to melt the raw materials on the upper and lower sides for 6 times. During the last smelting, reduce the current to 250A and continue to melt the upper and lower surfaces of the sample. At the end of smelting, quickly turn off the current to avoid undulations on the sample surface. After the sample is smelted, let the sample stand for 20 minutes. Then use a mechanical pump to pump the pressure in the furnace to less than 10MPa. Open the exhaust valve, open the furnace door when the pressure inside and outside the cavity is consistent, use a spray bottle to spray ethanol on the surface of the sample to cool it, and finally take a sample to obtain a silver-white disc-shaped niobium alloy block. Step 5: Place the niobium alloy block in a vacuum annealing furnace and use a mechanical pump and a diffusion pump furnace to pump the pressure in the furnace to 4×10 -3 Pa, heating from room temperature to 1550℃~1650℃ at a heating rate of 9~10℃ / min, keeping the temperature for 4 hours, and cooling with the furnace to obtain an annealed Nb alloy block; placing the Nb block obtained after annealing in a muffle furnace at 450℃~480℃ for 10 minutes, taking out the sample, and rolling the sample using a rolling mill; during the rolling process, the roller descends by 0.20mm~0.24mm at a time, and after a single rolling, the sample needs to be placed in a muffle furnace for 40s~50s, and the rolling is terminated when the sample thickness is reduced to about 0.15mm; the rolled sample is placed in a vacuum annealing furnace again, and a mechanical pump and a diffusion pump are used to make the pressure in the furnace reach 4×10 -3 After the temperature is below Pa, the sample is heated from room temperature to 1350°C-1450°C at a heating rate of 9-10°C / min and kept at this temperature for more than 1 hour. The sample is then cooled in the furnace to obtain the final Nb alloy sample.