In-situ core-shell structure second phase reinforced refractory alloy and preparation method thereof
By forming core-shell structured second-phase particles with HfO2 cores and B-enriched shells in situ within the refractory alloy matrix, the problem of performance degradation of traditional refractory alloys at high temperatures was solved, and the strength and ductility of the alloy at high temperatures were significantly improved.
Patent Information
- Application Number
- CN202510882421.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-10-17
AI Technical Summary
Traditional second-phase strengthening methods for refractory alloys suffer from problems such as weak interfacial bonding and particle agglomeration or decomposition at high temperatures, leading to a decline in alloy performance and making it difficult to maintain good comprehensive mechanical properties in ultra-high temperature environments.
A core-shell structured second-phase particle, consisting of an HfO2 core and a shell enriched with B element, was formed in situ in a refractory alloy matrix using a vacuum melting method. Through high-temperature deformation processing and vacuum annealing, an in-situ core-shell structured second-phase reinforced refractory alloy with good thermal stability and interfacial bonding ability was prepared.
The strength and ductility of the alloy are significantly improved, especially in maintaining good comprehensive mechanical properties under high temperature conditions. The room temperature tensile elongation of the Ta-WV-Hf-BO alloy exceeds 30%, the yield strength is about 800 MPa, and it still has a yield strength of about 140 MPa at a high temperature of 2000℃.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of structural materials, and particularly relates to an in-situ core-shell structure second phase strengthened refractory alloy and a preparation method thereof, which is suitable for aerospace, nuclear industry and other application scenarios with extremely high requirements on high-temperature performance. BACKGROUND
[0002] Refractory alloy, also known as high-melting-point alloy, refers to a kind of alloy material with a melting point higher than 1650℃. Due to its excellent high-temperature stability, this kind of material can maintain structural integrity and performance stability under high temperature, high pressure and corrosive environment, and is widely used in the preparation of key components under extreme service conditions such as aerospace and nuclear power. Common refractory alloy elements include tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta), vanadium (V) and rhenium (Re) etc. Among them, Ta and Nb have good ductility at room temperature, with tensile elongation exceeding 20%, but the strength is relatively low; Mo and W have high strength, but they show significant brittleness at room temperature and have poor formability. In order to meet the demand of ultra-high temperature service, refractory alloys with high-temperature strength and room-temperature processability need to be developed.
[0003] By combining refractory metal elements through solid solution strengthening, a refractory alloy with high-temperature strength and room-temperature processability is obtained. In addition, in order to meet the higher requirement of high-temperature service strength, second phase strengthening is introduced by adding second phase particles (such as carbides and nitrides), which significantly improves the room-temperature and high-temperature mechanical properties by using dislocation pinning effect. However, traditional second phase strengthening often uses external particles, which has the problems of weak interfacial bonding, particle agglomeration or decomposition at high temperature, etc., leading to performance degradation of the alloy in ultra-high temperature environment.
[0004] Therefore, it is a technical problem to be solved in the field to develop a preparation method for in-situ forming a second phase with high stability in a refractory alloy matrix, which can balance the room-temperature strength and toughness and ultra-high temperature performance. SUMMARY
[0005] The purpose of the present application is to provide an in-situ core-shell structure second phase strengthened refractory alloy and a preparation method thereof, which has good thermal stability and interfacial bonding ability, can significantly improve the strength and ductility of the alloy, and especially maintains good comprehensive mechanical properties at high temperature.
[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows:
[0007] Step 1: take 98.5-99.9% of base metal particles / powder and 0.1-1.5% of nano-sized HfB2 powder by mass percentage, and mix uniformly;
[0008] Step 2: load the mixed particles and powders into a vacuum melting furnace, and vacuumize to 1×10-3 Pa~6x10 -3 Pa, then high purity argon was filled again to 0.03-0.05 MPa, vacuum was extracted again to 1x10 -3 Pa~6x10 -3 Pa, then high purity argon was filled again to 0.03-0.05 MPa, vacuum was extracted again to 1x10
[0009] Step 3: the ingot was processed into a blank, the blank was heated to 300-500℃, rolling was performed with 5-10% deformation per pass, and the total deformation was 70-90% of the thickness of the original blank through multi-pass rolling to obtain an alloy sheet;
[0010] Step 4: the alloy sheet was placed in a vacuum furnace with a vacuum of 1x10 -3 Pa~6x10 -3 Pa, and was held at 1400-1800℃ for 1-2h, then furnace cooling was performed to complete the preparation of the in-situ core-shell structure second phase strengthened refractory alloy.
[0011] The base metal particles / powder is a mixture of at least two of tantalum (Ta), niobium (Nb), molybdenum (Mo), tungsten (W), vanadium (V), rhenium (Re), and hafnium (Hf) in any ratio, with a purity of greater than 99.95%.
[0012] The purity of the nanoscale HfB2 is greater than 99.95%.
[0013] The in-situ core-shell structure second phase strengthened refractory alloy obtained by the above preparation method comprises in-situ formed core-shell structure second phase particles, the core of the second phase particles is a HfO2 ceramic phase, and the shell layer is a transition layer rich in B elements, forming a B-HfO2 core-shell structure.
[0014] The second phase particles are core-shell structure with HfO2 as the core and a B element rich layer as the shell, and the particle size is 10-200 nm.
[0015] The present application adds HfB2 in the alloy, uses the high affinity between Hf and O, makes HfB2 powder and oxygen in the alloy and environment react in situ to generate the second phase particle B-HfO2 with core-shell structure during smelting. The formed second phase is composed of HfO2 ceramic core and B element enriched shell layer, and has fine particle size, regular morphology and uniform distribution. The second phase with core-shell structure has good thermal stability and interface bonding capacity, which can significantly improve the strength and ductility of the alloy, especially under high temperature conditions. The Ta-W-V-Hf-B-O alloy has a tensile elongation of more than 30% at room temperature, and a yield strength of about 800 MPa; at 2000℃ high temperature, it still has a yield strength of about 140 MPa, showing excellent high temperature performance. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 Microstructure of the second phase in the Ta-W-V-Hf-B-O alloy prepared in Example 1 of the present application.
[0017] Figure 2 Stress-strain curve of the Ta-W-V-Hf-B-O sample prepared in Example 1 of the present application under tensile test at 25℃.
[0018] Figure 3 Stress-strain curve of the Ta-W-V-Hf-B-O sample prepared in Example 1 of the present application under tensile test at 2000℃.
[0019] Figure 4 Microstructure of the second phase in the Nb-W-Hf-B-O alloy prepared in Example 2 of the present application.
[0020] Figure 5 Stress-strain curve of the Nb-W-Hf-B-O sample prepared in Example 2 of the present application under tensile test at 25℃. DETAILED DESCRIPTION
[0021] Example 1:
[0022] Step 1: weigh 86.8% Ta particles, 10% W powder, 3% V particles and 0.2% nano HfB2 powder according to the mass percentage, and mix uniformly.
[0023] Step 2: Put the mixed particles and powders into a vacuum smelting furnace, vacuumize to 1×10 -3 Pa, then fill high-purity argon to 0.03 MPa, vacuumize again to 1×10 -3 Pa, then fill high-purity argon to 0.03 MPa again; smelt the mixed powder at about 3000℃ and flip the ingot 7 times to obtain the ingot;
[0024] Step 3: The ingot is machined into a blank, the blank is heated to 450℃, and multi-pass rolling is performed with 5% deformation per pass, with a total cumulative deformation of 90% of the original blank thickness, to obtain an alloy sheet;
[0025] Step 4: The sheet is placed in a high vacuum furnace (vacuum degree 1×10 -3 Pa) and heated to 1600℃ for 1h, then furnace cooled, to complete the preparation of the in-situ core-shell structure second phase reinforced refractory alloy.
[0026] Figure 1 A is the second phase distribution in the alloy, it can be seen that the second phase particles in the material are fine, regular in morphology and uniformly distributed; Figure 1 B is a local enlarged view of the second phase, it can be seen that the size of the second phase is about 50nm; Figure 1 C is a three-dimensional atomic distribution map reconstructed by three-dimensional atom probe (APT) technology, showing that there is B element enrichment between the matrix and the second phase, and the second phase shows a core-shell structure, in which the core is a HfO2 ceramic phase and the shell is a transition layer rich in B element, forming a B-HfO2 core-shell structure.
[0027] From Figure 2 It can be seen that the room temperature tensile elongation of the Ta-W-V-Hf-B-O alloy with this ratio is more than 30%, and the yield strength is about 800MPa.
[0028] From Figure 3 It can be seen that the Ta-W-V-Hf-B-O alloy with this ratio still has a yield strength of about 140MPa at a high temperature of 2000℃.
[0029] Example 2:
[0030] Step 1: Take 81.8% Nb particles, 18% W powder and 0.2% nano-sized HfB2 powder by mass percentage, and mix them evenly.
[0031] Step 2: Put the mixed particles and powder into a vacuum melting furnace, and vacuumize to 1×10 -3 Pa, then fill high-purity argon gas to 0.03MPa, vacuumize again to 1×10 -3 Pa, then fill high-purity argon gas to 0.03MPa again; melt the mixed powder at about 3500℃ and flip the ingot 5 times to obtain an ingot;
[0032] Step 3: The ingot is machined into a blank, the blank is heated to 350℃, and multi-pass rolling is performed with 5% deformation per pass, with a total cumulative deformation of 90% of the original blank thickness, to obtain an alloy sheet;
[0033] Step 4: The sheet is placed in a high vacuum furnace (vacuum degree 1×10 -3Pa, and then the vacuum is extracted to 1x10
[0034] Figure 4 A is the second phase distribution in the alloy, it can be seen that the second phase particle size in the material is small, the morphology is regular and the distribution is uniform; Figure 4 B is a local enlarged view of the second phase, it can be seen that the size of the second phase is about 30nm; Figure 4 C is a three-dimensional atomic distribution map reconstructed by three-dimensional atom probe (APT) technology, showing that there is B element enrichment between the matrix and the second phase, and the second phase shows a core-shell structure, in which the core is HfO2 ceramic phase and the shell is a transition layer rich in B element, forming a B-HfO2 core-shell structure.
[0035] From Figure 5 It can be seen that the tensile elongation of the Nb-W-Hf-B-O alloy with this ratio at room temperature is about 18%, and the yield strength is about 550MPa. In comparison, the Nb-18W alloy without adding B-HfO2 core-shell structure shows significant room temperature brittleness, with elongation less than 5%, which shows that the fine and dispersed nanoscale core-shell structure of B-HfO2 second phase significantly improves the strength and toughness of the alloy.
[0036] Example 3:
[0037] Step 1: weigh 89.8% Ta particles, 9% W powder, 1% Re powder and 0.2% nanoscale HfB2 powder according to the mass percentage, and mix uniformly.
[0038] Step 2: Put the mixed particles and powders into a vacuum melting furnace, and extract the vacuum to 1x10 -3 Pa, and then extract the vacuum to 1x10 -3 Pa, and then extract the vacuum to 1x10
[0039] Step 3: Mechanically process the ingot into a blank, heat the blank to 350℃, and carry out multi-pass rolling with 5% deformation per pass, with a total cumulative deformation of 90% of the original blank thickness, to obtain an alloy sheet.
[0040] Step 4: Put the sheet into a high vacuum furnace (vacuum degree 1x10 -3 Pa), and then the vacuum is extracted to 1x10
[0041] Example 4:
[0042] Step 1: Take 89.8% Ta particles, 10% W powder and 0.2% nano-sized HfB2 powder by mass percentage, and mix them evenly.
[0043] Step 2: Put the mixed particles and powder into a vacuum melting furnace, and vacuumize to 1 x 10 -3 Pa, then fill high-purity argon to 0.03 MPa, vacuumize again to 1 x 10 -3 Pa, then fill high-purity argon again to 0.03 MPa; melt the mixed powder at about 3300℃ and flip the ingot 6 times to obtain an ingot;
[0044] Step 3: Machine the ingot into a blank, heat the blank to 350℃, and perform multi-pass rolling with 5% deformation per pass, with a total cumulative deformation of 90% of the original blank thickness, to obtain an alloy sheet;
[0045] Step 4: Place the sheet in a high-vacuum furnace (vacuum degree 1 x 10 -3 Pa), heat to 1450℃ for 1h, then furnace cool, to complete the preparation of the in-situ core-shell structure second-phase strengthened refractory alloy.
[0046] Example 5:
[0047] Step 1: Take 89.5% Ta particles, 10% W powder and 0.5% nano-sized HfB2 powder by mass percentage, and mix them evenly.
[0048] Step 2: Put the mixed particles and powder into a vacuum melting furnace, and vacuumize to 1 x 10 -3 Pa, then fill high-purity argon to 0.03 MPa, vacuumize again to 1 x 10 -3 Pa, then fill high-purity argon again to 0.03 MPa; melt the mixed powder at about 3300℃ and flip the ingot 7 times to obtain an ingot;
[0049] Step 3: Machine the ingot into a blank, heat the blank to 350℃, and perform multi-pass rolling with 5% deformation per pass, with a total cumulative deformation of 90% of the original blank thickness, to obtain an alloy sheet;
[0050] Step 4: Place the sheet in a high-vacuum furnace (vacuum degree 1 x 10 -3 Pa), heat to 1450℃ for 1h, then furnace cool, to complete the preparation of the in-situ core-shell structure second-phase strengthened refractory alloy.
[0051] Example 6:
[0052] Step 1: Take 93.5% Ta particles, 5% W powder and 1.5% nano-sized HfB2 powder by mass percentage, and mix them evenly.
[0053] Step 2: Put the mixed particles and powders into a vacuum melting furnace, vacuumize to 3x10 -3 Pa, then fill high-purity argon to 0.04 MPa, vacuumize to 3x10 -3 Pa again, then fill high-purity argon to 0.04 MPa again; melt the mixed powders at about 3200℃ and turn the ingot 7 times to obtain an ingot;
[0054] Step 3: Machine the ingot into a blank, heat the blank to 300℃, and carry out multi-pass rolling with 8% deformation per pass, with a total cumulative deformation of 70% of the thickness of the original blank, to obtain an alloy sheet;
[0055] Step 4: Place the sheet in a high-vacuum furnace (vacuum degree 3x10 -3 Pa), heat to 1400℃ and keep for 2h, then furnace cool, to complete the preparation of the in-situ core-shell structure second-phase strengthened refractory alloy.
[0056] Example 7:
[0057] Step 1: Take 94.8% Nb particles, 4.2% W powder, and 1% nano-sized HfB2 powder by mass percentage, and mix uniformly.
[0058] Step 2: Put the mixed particles and powders into a vacuum melting furnace, vacuumize to 5x10 -3 Pa, then fill high-purity argon to 0.05 MPa, vacuumize to 5x10 -3 Pa again, then fill high-purity argon to 0.05 MPa again; melt the mixed powders at about 3000℃ and turn the ingot 5 times to obtain an ingot;
[0059] Step 3: Machine the ingot into a blank, heat the blank to 500℃, and carry out multi-pass rolling with 10% deformation per pass, with a total cumulative deformation of 80% of the thickness of the original blank, to obtain an alloy sheet;
[0060] Step 4: Place the sheet in a high-vacuum furnace (vacuum degree 5x10 -3 Pa), heat to 1500℃ and keep for 2h, then furnace cool, to complete the preparation of the in-situ core-shell structure second-phase strengthened refractory alloy.
[0061] Example 8:
[0062] Step 1: Take 95.8% Nb particles, 3% Mo particles, and 1.2% nano-sized HfB2 powder by mass percentage, and mix uniformly.
[0063] Step 2: Put the mixed particles and powders into a vacuum melting furnace, vacuumize to 2x10 -3 Pa, then fill high-purity argon to 0.03 MPa, vacuumize to 2x10 -3Pa, and then high-purity argon gas was filled again to 0.03 MPa; the mixed powder was smelted at about 3100 ° C and the ingot was turned over 5 times to obtain an ingot;
[0064] Step 3: The ingot is machined into a billet, the billet is heated to 400°C, and multiple rolling passes are performed with a deformation of 6% per pass, with the total deformation amount being 80% of the original billet thickness, to obtain an alloy sheet;
[0065] Step 4: Place the sheet in a high vacuum furnace (vacuum degree 6×10 -3 Pa), heated to 1800 ° C and kept for 1 hour, and then furnace cooled to complete the preparation of the refractory alloy with in-situ core-shell structure second phase reinforcement.
[0066] Example 9:
[0067] Step 1: Weigh 96.9% of Nb particles, 3% of Hf particles and 0.1% of nano-scale HfB2 powder by mass percentage and mix them evenly.
[0068] Step 2: Load the mixed particles and powder into the vacuum melting furnace and evacuate to 6×10 -3 Pa, filled with high-purity argon gas to 0.03 MPa and then evacuated to 6×10 -3 Pa, and then argon again to 0.03MPa; melt the mixed powder at about 3000 ° C and turn the ingot 5 times to obtain an ingot;
[0069] Step 3: The ingot is machined into a billet, the billet is heated to 350°C, and multiple rolling passes are performed with a deformation of 5% per pass, and the cumulative total deformation is 90% of the original billet thickness to obtain an alloy sheet;
[0070] Step 4: Place the sheet in a high vacuum furnace (vacuum degree 1×10 -3 Pa), heated to 1700 ° C and kept for 1.2 h, and then furnace cooled to complete the preparation of the refractory alloy with in situ core-shell structure second phase reinforcement.
[0071] The invention adopts a vacuum melting method to prepare an in-situ core-shell structure second phase reinforced refractory alloy in a laboratory, and the material is deformed and vacuum high-temperature annealed. The related results show that the nano second phase HfB2 forms a core-shell structure second phase particle in the refractory alloy. The second phase particle in the prepared alloy shows obvious core-shell structure characteristics: the core is HfO ceramic phase, and the shell is an interface transition layer rich in boron elements. The strength of the Ta-W alloy after dispersion strengthening at room temperature is obviously improved, and the core-shell second phase particle effectively suppresses dislocation movement and improves interface bonding force, thereby significantly enhancing the mechanical properties of the alloy. Taking Ta-W-V-Hf-B-O alloy as an example, the room temperature tensile elongation is more than 30%, and the yield strength is about 800 MPa; at 2000 DEG C high temperature condition, it still has a yield strength of about 140 MPa, showing excellent high temperature performance, and the high temperature strength is improved by more than 70% compared with Ta-10W, and has excellent high temperature strength; the Nb-W-Hf-B-O system is reinforced by the core-shell structure second phase, and the room temperature tensile elongation is improved from less than 5% to 18%, and the yield strength is about 550 MPa. The invention adopts melting, large deformation processing and vacuum high-temperature annealing method, which has the advantages of simple equipment requirement, easy to realize experimental condition, accurate controllable sample processing, excellent surface quality and other advantages, realizes the exploration and development of new refractory alloy system in the laboratory.
Claims
1. A method for preparing an in-situ core-shell structured second phase strengthened refractory alloy, characterized in that The following steps are involved: Step 1: Take 98.5-99.9% of base metal particles / powder and 0.1-1.5% of nano-scale HfB2 powder by mass percentage and mix them evenly; Step 2: Load the mixed particles and powder into a vacuum melting furnace and evacuate to 1×10 -3 Pa~6×10 -3 Pa, high-purity argon was filled to 0.03-0.05 MPa, and vacuumed again to 1×10 -3 Pa~6×10 -3 Pa, and then high-purity argon is filled again to 0.03-0.05MPa, and then the mixed powder is smelted at 3000℃~3500℃ and turned over 5-7 times to obtain an ingot; Step 3: Processing the ingot into a billet, heating the billet to 300°C to 500°C, and rolling the billet with a deformation of 5% to 10% per pass. After multiple rolling passes, the total deformation is 70% to 90% of the original billet thickness to obtain an alloy sheet. Step 4: Place the alloy sheet in a vacuum of 1×10 -3 Pa~6×10 -3 Pa vacuum furnace, keep warm at 1400℃~1800℃ for 1-2h, then cool the furnace to complete the preparation of the refractory alloy with in-situ core-shell structure second phase reinforcement.
2. The method for preparing an in-situ core-shell structured second phase strengthened refractory alloy according to claim 1, characterized in that: The matrix metal particles / powder are formed by mixing at least two elements of tantalum (Ta), niobium (Nb), molybdenum (Mo), tungsten (W), vanadium (V), rhenium (Re), and hafnium (Hf) with a purity greater than 99.95% in any proportion.
3. The method for preparing an in-situ core-shell structured second phase strengthened refractory alloy according to claim 1, characterized in that: The purity of the nano-scale HfB2 is greater than 99.95%.
4. A refractory alloy with an in-situ core-shell structure second phase reinforcement obtained by the preparation method as described in any one of claims 1 to 3 comprises in-situ formed core-shell structure second phase particles, wherein the core of the second phase particles is an HfO2 ceramic phase, and the shell layer is a transition layer enriched in B element, constituting a B-HfO2 core-shell structure.
5. The in-situ core-shell structure second phase strengthened refractory alloy according to claim 4, characterized in that: The second phase particles are a core-shell structure with HfO2 as the core and a B element-enriched layer as the shell, and the particle size is 10-200 nm.