High-strength plastic layered molybdenum-rhenium alloy and preparation process thereof

Abstract

The invention relates to a high-strength plastic layered molybdenum-rhenium alloy and a preparation process thereof, the molybdenum-rhenium alloy has a layered structure with soft and hard alternated, a gap is arranged between every two layers, and the thickness of each layer is 10-50 [mu] m. Mo powder, Re powder and strengthening phase powder are evenly mixed and then subjected to high-temperature impurity removal, obtained molybdenum-rhenium alloy composite powder is subjected to cold isostatic pressing, pressureless sintering and hot pressing sintering, a fine and compact matrix structure is obtained, and then circulating high-temperature rolling and annealing are carried out, so that the soft-hard alternate high-strength plastic layered molybdenum-rhenium alloy is obtained. By introducing the strengthening phase to refine the average grain size of the molybdenum-rhenium alloy, the grain boundary density of the molybdenum-rhenium alloy is increased, the recrystallization temperature of the molybdenum-rhenium alloy is increased, and circulating high-temperature rolling and annealing can be carried out, so that a soft-hard alternate layered structure is induced to be generated, the limitation of the hot working size of a molybdenum-rhenium alloy pipeline is removed, and meanwhile, the Re content is greatly reduced; the cost is saved by more than 80%, and the service requirement of an extremely severe environment (the service temperature gt and 1500 DEG C) is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of molybdenum alloy preparation, and particularly relates to a high-strength and high-ductility laminated molybdenum-rhenium alloy and a preparation process thereof. Background Art

[0002] Molybdenum-rhenium alloys have become important candidate materials for structural materials in advanced nuclear reactors such as high-temperature nuclear fission reactors and fusion reactors due to their good thermal properties, mechanical properties, workability, and corrosion resistance. The commonly used molybdenum-rhenium alloys in nuclear reactors are Mo-41%Re and Mo-47.5%Re alloys. Research shows that the Re element has a relatively high thermal neutron absorption cross-section. When the content is relatively high, element transmutation is likely to occur during irradiation, causing embrittlement of the material and affecting the safety of nuclear reactors. However, with the decrease in the rhenium content, the high sensitivity of molybdenum-rhenium alloys to impurities such as oxygen intensifies, reducing the grain boundary cohesion and fracture toughness. Low-rhenium alloys exhibit problems such as insufficient high-temperature strength, poor ductility at room temperature, and recrystallization embrittlement in practical applications, and it is difficult to meet the requirements of the structural forming of thin-walled tubes in the reactor core and service in extreme environments.

[0003] As a strong solid solution strengthener, rhenium fundamentally changes the thermodynamic and kinetic behaviors of molybdenum-rhenium alloys. Research shows that the Gibbs free energy of the Re−O reaction at high temperatures is greater than that of the Mo−O reaction, causing oxygen to react preferentially with molybdenum to form oxides such as MoO3, resulting in the enrichment of rhenium elements in the molybdenum-based solid solution, thereby reducing the plasticity and toughness of the material. In addition, first-principles calculations show that removing oxygen in low-rhenium alloys can enhance grain boundary cohesion and improve the thermal stability of the alloy. Therefore, any method that can reduce the impurity content at grain boundaries can effectively improve the strength and ductility of molybdenum-rhenium alloys. Research shows that impurity element purification helps to improve the strength and toughness of molybdenum-rhenium alloys.

[0004] The second-phase strengthening is the most important way to improve the properties of molybdenum alloys. The structure, morphology of the second phase and the interfacial relationship with the matrix are the key factors affecting the properties of molybdenum alloys. Wang et al. investigated the effect of La2O3 content on the room-temperature tensile properties of Mo-14Re alloys. The results showed that with the increase of La2O3 content, the room-temperature elongation of the alloy changed little. At 1100 °C, the tensile strength of Mo-14Re-1.7La2O3 was as high as 410 MPa, but the elongation was only 9% due to the inconsistent deformation between the oxide and the matrix during the deformation process. Compared with oxides, ZrC particles have been proven to be able to adsorb oxygen impurities in the molybdenum matrix to form a new ZrO2 phase, purifying and strengthening the molybdenum matrix. Secondly, carbide particles tend to form coherent or semi-coherent interfaces with the molybdenum matrix, enhancing the interfacial bonding strength and thus effectively strengthening the matrix. Jing et al. successfully prepared nanostructured Mo-ZrC alloys with excellent room-temperature and high-temperature mechanical properties through the dispersion and interface control of nano-ZrC particles. The room-temperature tensile strength was as high as 928 MPa, and the high-temperature tensile strength at 1000 °C reached an unprecedented 562 MPa, but the toughness was lower than that of pure molybdenum. None of the above methods can achieve the simultaneous improvement of the strength and plasticity-toughness of molybdenum alloys.

[0005] There are still obvious gaps in the current research on the second-phase strengthening of molybdenum-rhenium alloys. Moreover, the solid solution effect of rhenium elements causes significant lattice distortion in the molybdenum matrix, resulting in essential differences in the phase interface behavior between it and the pure molybdenum matrix. How to break through and solve the problem of the inversion of strength and toughness of molybdenum-rhenium alloys and achieve good thermal stability of molybdenum-rhenium alloys at higher temperatures is a scientific problem that urgently needs to be solved. Summary of the Invention

[0006] To solve the above problems, the present invention provides a high-strength and ductile laminated molybdenum-rhenium alloy and its preparation process. The high-strength and ductile laminated molybdenum-rhenium alloy is prepared by a cyclic hot rolling and annealing process. By introducing strengthening phases, the average grain size of the molybdenum-rhenium alloy matrix is reduced, the grain boundaries of the molybdenum-rhenium alloy are increased, and the recrystallization temperature of the molybdenum-rhenium alloy is increased, enabling the molybdenum-rhenium alloy to be cyclic hot rolled and annealed, thereby obtaining a laminated matrix. Through annealing-induced grain recrystallization, the recrystallized grains are newly formed equiaxed grains without defects, which are hard phases, and there are a large number of dislocations and work hardening in the grains that have not undergone recrystallization, which are soft phases. Usually, recrystallization starts from the grain boundaries and diffuses layer by layer inward with the extension of time. By controlling the annealing temperature and time, a laminated structure of hard and soft phases can be induced, improving the room-temperature and high-temperature tensile strengths of the molybdenum-rhenium alloy, while improving the plasticity of the molybdenum-rhenium alloy, achieving the simultaneous improvement of the strength and plasticity of the molybdenum-rhenium alloy, and providing a broader application prospect for the application of molybdenum-rhenium alloys in more extreme environments.

[0007] The primary objective of the present invention is to provide a high-strength and high-ductility laminated molybdenum-rhenium alloy. This molybdenum-rhenium alloy has a laminated structure with alternating hard and soft layers, with gaps between the layers, and the thickness of each layer is 10 - 50 μm. Its tensile strength at room temperature is 610 - 700 MPa, and the elongation is 18 - 23%; the tensile strength at 1000 °C is 420 - 450 MPa, and the elongation is 15 - 25%.

[0008] Another objective of the present invention is to provide a preparation process for the above-mentioned high-strength and high-ductility laminated molybdenum-rhenium alloy with alternating hard and soft layers, which specifically includes the following steps: (1) Place Mo powder, Re powder, and reinforcing phase powder in a planetary ball mill for uniform mixing to obtain a molybdenum-rhenium composite powder reinforced by a secondary phase; the reinforcing phase is at least one of ZrO2, ZrC, and Ti3AlC2; by weight percentage, the Re powder accounts for 5% - 14% of the weight of the mixed powder, the reinforcing phase accounts for 0.5% - 3% of the weight of the mixed powder, and the rest is molybdenum powder. The mixed powder refers to the mixed powder of Mo powder, Re powder, and reinforcing phase powder; (2) Remove impurities from the molybdenum-rhenium composite powder obtained in step (1) in a hydrogen atmosphere to obtain a molybdenum-rhenium alloy composite powder; (3) Subject the molybdenum-rhenium alloy composite powder obtained in step (2) to cold isostatic pressing, pressureless sintering in a hydrogen atmosphere, and hot isostatic pressing sintering in sequence to obtain a fine-grained molybdenum-rhenium alloy reinforced by a secondary phase; (4) Subject the fine-grained molybdenum-rhenium alloy reinforced by a secondary phase obtained in step (3) to cyclic hot rolling and annealing. Introduce a laminated structure through hot large-deformation rolling to prepare a laminated molybdenum-rhenium alloy plate; the blooming temperature of the hot large-deformation rolling is 1350 - 1450 °C, one fire and one pass, the single-pass deformation amount is 30 - 35%, and the total deformation amount > 85%; (5) Anneal the laminated molybdenum-rhenium alloy plate obtained in step (4) in a hydrogen atmosphere to induce the formation of a high-strength and high-ductility laminated molybdenum-rhenium alloy with alternating hard and soft layers.

[0009] Preferably, in step (1), the rotation speed of the planetary ball mill is 170 - 200 r / min, the mixing time is 3 - 5 h, and the ball-to-material ratio is 10:1.

[0010] Preferably, in step (1), the average particle size of the Mo powder is 2 - 3 μm, the average particle size of the Re powder is 6 - 10 μm, and the size of the reinforcing phase is 50 - 200 nm.

[0011] Preferably, in step (2), the hydrogen reduction temperature is 850 - 900 °C, the hydrogen flow rate is 30 - 35 m 3 / h, and the heat preservation time is 1 - 2 h.

[0012] Preferably, in step (3), the cold isostatic pressing green compact is processed by a cold isostatic press, with a pressure of 160 - 200 MPa and a pressure holding time of 20 - 30 min; non-pressure sintering is carried out using a non-pressure intermediate frequency furnace with hydrogen introduced, the sintering temperature is 1500 - 1700 °C, the heat preservation time is 2 - 5 h, and the hydrogen flow rate is 6 - 8 m 3 / h; argon is selected for protection during the hot isostatic pressing sintering process, the sintering temperature is 1700 - 1900 °C, the pressure is 170 - 190 MPa, and the heat preservation time is 1 - 2 h.

[0013] Furthermore, the density of the secondary phase - strengthened fine - grained molybdenum - rhenium alloy prepared according to the above process is greater than 99%, the average grain size is 15 - 30 μm, and the impurity oxygen element content is less than 16 ppm.

[0014] Preferably, in step (5), the annealing temperature is 1200 - 1300 °C and the heat preservation time is 1 h.

[0015] The high - strength and high - plasticity laminated molybdenum - rhenium alloy prepared according to the above method has a laminated structure with alternating hard and soft layers, there are gaps between the layers, and the thickness of each layer is 10 - 50 μm; its room - temperature tensile strength is 610 - 700 MPa, and the elongation is 18 - 23%; the high - temperature tensile strength at 1000 °C is 420 - 450 MPa, and the elongation is 15 - 25%.

[0016] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above - mentioned technical solution, the present invention can achieve considerable technical progressiveness and practicability, and has wide application value. It has at least the following advantages: In the present invention, Mo powder, Re powder and strengthening phase powder are placed in a planetary ball mill for uniform mixing to obtain a molybdenum-rhenium composite powder strengthened by a secondary phase. After removing impurities with high-temperature hydrogen, the powder is subjected to cold isostatic pressing, pressureless sintering and hot pressing sintering to obtain a fine and dense matrix structure. Then, cyclic hot rolling and annealing are carried out to finally obtain a high-strength and high-plasticity laminated molybdenum-rhenium alloy with alternating hard and soft phases. Removing impurities from the powder after ball milling can ensure that the powder has a low impurity oxygen content. Then, selecting low-temperature pressureless sintering can further purify impurities and effectively avoid grain growth caused by high-temperature sintering. The blank obtained by cold isostatic pressing is sintered to closed pores by pressureless sintering to prepare for hot isostatic pressing sintering. Finally, hot isostatic pressing is selected to prepare a molybdenum-rhenium alloy blank with a fine grain structure and high density. The secondary phase can effectively hinder dislocation movement, inhibit grain growth, promote the formation of a fine-grained structure, and increase the recrystallization temperature of the molybdenum-rhenium alloy during the sintering process, enabling the molybdenum-rhenium alloy to be subjected to blooming rolling at a higher temperature. By selecting cyclic hot rolling and annealing, a laminated molybdenum-rhenium alloy is obtained. By controlling the annealing temperature and time, a laminated structure with alternating hard and soft phases is induced, improving the room-temperature / high-temperature tensile strength of the molybdenum-rhenium alloy and simultaneously improving the plasticity of the molybdenum-rhenium alloy, achieving the simultaneous improvement of the strength and plasticity of the molybdenum-rhenium alloy.

[0017] The high-strength and high-plasticity laminated molybdenum-rhenium alloy with alternating hard and soft phases prepared by the present invention has a recrystallization temperature increased by more than 200 °C compared with the pure molybdenum-rhenium alloy, can break free from the size limitation of hot processing of molybdenum-rhenium alloy pipes, and at the same time greatly reduce the Re content, saving more than 80% of the cost and meeting the service requirements in extremely harsh environments (service temperature > 1500 °C). Description of the Drawings

[0018] Figure 1 It is the room-temperature tensile curve of the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Examples 1 to 3 and the high-performance molybdenum-rhenium alloy prepared in the comparative example.

[0019] Figure 2 It is the high-temperature tensile curve at 1000 °C of the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Examples 1 to 3 and the high-performance molybdenum-rhenium alloy prepared in the comparative example.

[0020] Figure 3 It is the SEM fracture surface diagram of the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Example 1.

[0021] Figure 4 It is the SEM fracture surface diagram of the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Example 2.

[0022] Figure 5 It is the SEM fracture surface diagram of the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Example 3.

[0023] Figure 6 It is the SEM fracture surface diagram of the high-performance molybdenum-rhenium alloy prepared in the comparative example.

[0024] Figure 7 are Kernel Average Misorientation (KAM) maps of the high-strength and high-ductility laminated Mo-Re alloys prepared in Examples 1 to 3 and the high-performance Mo-Re alloys prepared in the comparative examples.

[0025] Figure 8 are Grain Orientation Spread (GOS) maps of the high-strength and high-ductility laminated Mo-Re alloys prepared in Examples 1 to 3 and the high-performance Mo-Re alloys prepared in the comparative examples. Detailed implementation manners To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0026] The present invention will be described in detail below with specific embodiments. For those not specified in the following embodiments, they are all carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials and reagents used without indicating the manufacturer can be obtained as conventional products through commercial purchase.

[0027] Example 1 (1) Put Mo powder, Re powder and ZrO2 powder into a planetary ball mill and mix them evenly for 5 h. The rotation speed of the planetary ball mill is 170 r / min, and the ball-to-material ratio is 10:1 to obtain a secondary-phase strengthened Mo-Re composite powder; among them, the average particle size of Mo powder is 3 μm, the average particle size of Re powder is 8 μm, and the particle size of ZrO2 powder is 100 nm; the weights of Re powder and ZrO2 powder respectively account for 5% and 1.0% of the total weight of the mixed powder, and the rest is molybdenum powder; the mixed powder refers to the mixed powder of Mo powder, Re powder and ZrO2 powder; (2) Carry out high-temperature impurity removal on the secondary-phase strengthened Mo-Re composite powder obtained in step (1) in a hydrogen atmosphere. The hydrogen reduction temperature is 880 °C, and the hydrogen flow rate is 30 m 3 / h, keep the temperature for 1 h to obtain a Mo-Re alloy composite powder; (3) Press the Mo-Re alloy composite powder obtained in step (2) in a cold isostatic press at 180 MPa for 25 min, and then carry out pressureless sintering at 1600 °C for 5 h in a pressureless intermediate frequency furnace. Hydrogen is introduced during the pressureless sintering, and the hydrogen flow rate is 8 m 3 / h; then carry out hot isostatic pressing sintering. Argon is selected for protection during the hot isostatic pressing sintering process. The sintering temperature is 1700 °C, the pressure is 190 MPa, and the holding time is 1 h to obtain a secondary-phase strengthened fine-grained Mo-Re alloy with a relative density of 99.2%, an average grain size of 15.8 μm, and an impurity oxygen element content of 16 ppm. (4) Subject the second-phase strengthened fine-grained molybdenum-rhenium alloy obtained in step (3) to cyclic hot rolling and annealing. Introduce a layered structure through cyclic hot rolling with large deformation, and prepare a layered molybdenum-rhenium alloy plate. The billet heating temperature for rolling is 1380 °C, one-pass per heat, the single-pass deformation amount is 32%, roll for 6 passes, and the total deformation amount is 90.1%; (5) Anneal the layered molybdenum-rhenium alloy plate obtained in step (4) in a hydrogen atmosphere to induce the formation of a high-strength and high-ductility layered molybdenum-rhenium alloy plate with alternating soft and hard phases. The annealing temperature is 1200 °C, and the holding time is 1 h.

[0028] After testing, the room-temperature tensile strength of the obtained high-strength and high-ductility layered molybdenum-rhenium alloy plate with alternating soft and hard phases is 618 MPa, the elongation is 22.8%, the tensile strength at 1000 °C is 447 MPa, and the elongation is 16.5%.

[0029] Example 2 (1) Place Mo powder, Re powder, and ZrC powder in a planetary ball mill and mix them evenly for 4 h. The rotation speed of the planetary ball mill is 190 r / min, and the ball-to-powder ratio is 10:1 to obtain a second-phase strengthened molybdenum-rhenium composite powder. Among them, the average particle size of Mo powder is 2.5 μm, the average particle size of Re powder is 6 μm, and the particle size of ZrC powder is 50 nm; the weights of Re powder and ZrC powder account for 14% and 0.6% of the total weight of the mixed powder, respectively, and the rest is molybdenum powder; the mixed powder refers to the mixed powder of Mo powder, Re powder, and ZrC powder; (2) Carry out high-temperature impurity removal on the second-phase strengthened molybdenum-rhenium composite powder obtained in step (1) in a hydrogen atmosphere. The hydrogen reduction temperature is 900 °C, the hydrogen flow rate is 35 m 3 / h, hold for 1.5 h to obtain a molybdenum-rhenium alloy composite powder; (3) Press the molybdenum-rhenium alloy composite powder obtained in step (2) in a 200 MPa cold isostatic press for 20 min, and then carry out pressureless sintering at 1700 °C for 3 h in a pressureless intermediate frequency furnace. Hydrogen is introduced during pressureless sintering, and the hydrogen flow rate is 7 m 3 / h; then carry out hot isostatic pressing sintering. Argon is selected for protection during the hot isostatic pressing sintering process. The sintering temperature is 1900 °C, the pressure is 180 MPa, and the holding time is 1.5 h to obtain a second-phase strengthened fine-grained molybdenum-rhenium alloy with a relative density of 99.5%, an average grain size of 17.6 μm, and an impurity oxygen element content of 12 ppm; (4) Subject the second-phase strengthened fine-grained molybdenum-rhenium alloy obtained in step (3) to cyclic hot rolling and annealing. Introduce a layered structure through cyclic hot rolling with large deformation, and prepare a layered molybdenum-rhenium alloy plate. The billet heating temperature for rolling is 1400 °C, one-pass per heat, the single-pass deformation amount is 30%, roll for 7 passes, and the total deformation amount is 92.7%; (5) Anneal the laminated molybdenum-rhenium alloy plate obtained in step (4) in a hydrogen atmosphere to induce the formation of a high-strength and high-ductility laminated molybdenum-rhenium alloy plate with alternating hard and soft phases. The annealing temperature is 1250 °C and the holding time is 1.5 h.

[0030] After testing, the room-temperature tensile strength of the obtained high-strength and high-ductility laminated molybdenum-rhenium alloy plate with alternating hard and soft phases is 692 MPa, the elongation is 21.1%, the tensile strength at 1000 °C is 435 MPa, and the elongation is 23.5%.

[0031] Example 3 (1) Place Mo powder, Re powder, and Ti3AlC2 powder in a planetary ball mill and mix them evenly for 4 h. The rotation speed of the planetary ball mill is 200 r / min, and the ball-to-powder ratio is 10:1 to obtain a secondary-phase strengthened molybdenum-rhenium composite powder. Among them, the average particle size of the Mo powder is 2 μm, the average particle size of the Re powder is 7 μm, and the particle size of the Ti3AlC2 powder is 200 nm. The weights of the Re powder and Ti3AlC2 powder respectively account for 5% and 2.0% of the total weight of the mixed powder, and the rest is molybdenum powder. The mixed powder refers to the mixed powder of Mo powder, Re powder, and Ti3AlC2 powder; (2) Perform high-temperature impurity removal on the secondary-phase strengthened molybdenum-rhenium composite powder obtained in step (1) in a hydrogen atmosphere. The hydrogen reduction temperature is 850 °C, the hydrogen flow rate is 32 m 3 / h, and hold for 2 h; (3) Press the molybdenum-rhenium alloy composite powder obtained in step (2) in a cold isostatic press at 160 MPa for 30 min, and then perform pressureless sintering in a pressureless intermediate-frequency furnace at 1500 °C for 5 h. Hydrogen is introduced during the pressureless sintering, and the hydrogen flow rate is 6 m 3 / h; Subsequently, perform hot isostatic pressing sintering. Argon is used for protection during the hot isostatic pressing sintering process. The sintering temperature is 1800 °C, the pressure is 170 MPa, and the holding time is 2 h to obtain a secondary-phase strengthened fine-grained molybdenum-rhenium alloy with a relative density of 99.1%, an average grain size of 29.6 μm, and an impurity oxygen element content of 15 ppm; (4) Perform cyclic hot rolling and annealing on the secondary-phase strengthened fine-grained molybdenum-rhenium alloy obtained in step (3). Introduce a laminated structure through cyclic hot rolling with large deformation to prepare a laminated molybdenum-rhenium alloy plate. The blooming temperature of the rolling is 1450 °C, one fire and one pass, the single-pass deformation amount is 35%, and it is rolled for 5 passes with a total deformation amount of 88.4%; (5) Anneal the laminated molybdenum-rhenium alloy plate obtained in step (4) in a hydrogen atmosphere to induce the formation of a high-strength and high-ductility laminated molybdenum-rhenium alloy plate with alternating hard and soft phases. The annealing temperature is 1300 °C and the holding time is 1 h.

[0032] After testing, the room-temperature tensile strength of the obtained high-strength and high-plasticity laminated molybdenum-rhenium alloy plate with alternating hard and soft layers is 653 MPa, the elongation is 18.5%, the tensile strength at 1000 °C is 422 MPa, and the elongation is 15%.

[0033] Comparative example (1) Put Mo powder and Re powder into a planetary ball mill and mix them evenly for 5 h. The rotation speed of the planetary ball mill is 170 r / min, and the ball-to-material ratio is 10:1 to obtain a molybdenum-rhenium composite powder; among them, the average particle size of Mo powder is 3 μm, the average particle size of Re powder is 8 μm, and the weight percentage of Re powder in the molybdenum-rhenium mixed powder is 5%, and the rest is molybdenum powder; (2) Remove impurities from the molybdenum-rhenium composite powder obtained in step (1) at high temperature in a hydrogen atmosphere. The hydrogen reduction temperature is 880 °C, the hydrogen flow rate is 30 m 3 / h, and keep the temperature for 1 h to obtain a molybdenum-rhenium alloy composite powder; (3) Press the molybdenum-rhenium alloy composite powder obtained in step (2) in a cold isostatic press at 180 MPa for 25 min, and then sinter it without pressure in a medium-frequency furnace at 1600 °C for 3 h. Hydrogen is introduced during the non-pressure sintering, and the hydrogen flow rate is 8 m 3 / h; then perform hot isostatic pressing sintering. Argon is used for protection during the hot isostatic pressing sintering process. The sintering temperature is 1700 °C, the pressure is 190 MPa, and the holding time is 1 h to obtain a molybdenum-rhenium alloy with a relative density of 99.2%, an average grain size of 63.8 μm, and an impurity oxygen element content of 17 ppm; (4) Perform cyclic hot rolling and annealing on the molybdenum-rhenium alloy obtained in step (3). The billet-opening temperature for rolling is 1350 °C, one fire and one pass, the single-pass deformation amount is 32%, and it is rolled for 6 passes with a total deformation amount of 90.1% to obtain a molybdenum-rhenium alloy plate; (5) Anneal the molybdenum-rhenium alloy plate obtained in step (4) in a hydrogen atmosphere. The annealing temperature is 1200 °C, and the holding time is 1 h to obtain a high-performance molybdenum-rhenium alloy plate.

[0034] After testing, the room-temperature tensile strength of the prepared high-performance molybdenum-rhenium alloy plate is 501 MPa, the elongation is 12.5%, the tensile strength at 1000 °C is 400 MPa, and the elongation is 13%.

[0035] Figure 1 It is the room-temperature tensile curve of the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Examples 1-3 and the high-performance molybdenum-rhenium alloy prepared in the comparative example. It can be seen that the high-strength and high-plasticity laminated molybdenum-rhenium alloy prepared in Examples 1-3 has higher room-temperature tensile strength and elongation. The laminated structure can break through the problem of the strength and plasticity inversion of the molybdenum-rhenium alloy and realize the synchronous improvement of the strength and plasticity of the molybdenum-rhenium alloy.

[0036] Figure 2 The high-strength and high-ductility laminated Mo-Re alloys prepared in Examples 1 to 3 and the high-performance Mo-Re alloy prepared in the comparative example are shown in the high-temperature tensile curves at 1000 °C. It can be seen that the high-strength and high-ductility laminated Mo-Re alloys prepared in Examples 1 to 3 not only have good room-temperature strength and ductility but also have good high-temperature strength and ductility. They can break free from the size limitations of hot processing of Mo-Re alloy pipes, significantly reduce the Re content, save more than 80% of the cost, and can meet the service requirements in extremely harsh environments (service temperature > 1500 °C).

[0037] Figure 3 The SEM fracture surface diagram of the high-strength and high-ductility laminated Mo-Re alloy prepared in Example 1 can clearly show the laminated morphology in the Mo-Re alloy. There are gaps between layers, and the thickness of each layer is approximately 10 - 50 μm.

[0038] Figure 4 The SEM fracture surface diagram of the high-strength and high-ductility laminated Mo-Re alloy prepared in Example 2 also has obvious laminated structural characteristics. There are gaps between layers, and the thickness of each layer is approximately 10 - 30 μm.

[0039] Figure 5 The SEM fracture surface diagram of the high-strength and high-ductility laminated Mo-Re alloy prepared in Example 3 can show the laminated structural characteristics, but the laminated structure is less significant compared with Figure 3 and Figure 4 This may be because the size of the secondary phase is larger, and the initial grain size of the secondary phase is larger than that in Example 1 and Example 2, which is not conducive to the formation of the laminated structure.

[0040] Figure 6 The SEM fracture surface diagram of the Mo-Re alloy prepared in the comparative example does not have laminated characteristics and is a typical brittle fracture morphology.

[0041] Figure 7 The Kernel Average Misorientation (KAM) diagrams of the high-strength and high-ductility laminated Mo-Re alloys prepared in Examples 1 to 3 and the high-performance Mo-Re alloy prepared in the comparative example are shown. The higher the GND value, the greater the degree of deformation of the alloy and the higher the dislocation density. Figure 7 The transition from blue to red in [Figure] indicates a gradual increase in the local misorientation. The distribution of the local misorientation is uneven. Usually, the misorientation at the grain boundaries is higher, indicating that dislocations accumulate severely at the grain boundaries and the deformation storage energy is higher, which promotes the occurrence of dynamic recrystallization. After adding the second-phase particles, more sub-grain boundaries are generated after annealing of the Mo-Re alloy. These sub-grain boundaries store a higher dislocation density by capturing and hindering the movement of dislocations. Therefore, the GND values of Mo-Re-ZrO2, Mo-Re-ZrC, and Mo-Re-Ti3AlC2 alloys are greater than the GND value of Mo-Re. By regulating the annealing temperature and time to induce grain recrystallization, the dislocation density shows a laminated distribution.

[0042] Figure 8 It is the grain orientation spread (GOS) map of the high-strength and high-ductility laminated Mo-Re alloys prepared in Examples 1 to 3 and the high-performance Mo-Re alloys prepared in the comparative examples. The red part represents the recrystallized region. The recrystallized regions of Examples 1 to 3 show an obvious laminated distribution, while almost all recrystallization occurs in the comparative example. The dynamic recrystallization ratio of the Mo-Re-ZrO2, Mo-Re-ZrC, and Mo-Re-Ti3AlC2 alloys is less than that of the Mo-Re alloy because the addition of fine and dispersed second-phase particles produces a significant Zener drag effect, delaying the occurrence of dynamic recrystallization.

[0043] The above are only examples of the present invention and do not impose any formal limitations on the present invention. The present invention may also have other forms of embodiments based on the above structures and functions, which will not be listed one by one. Therefore, any person skilled in the art, without departing from the scope of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-strength and high-plasticity laminated molybdenum-rhenium alloy, characterized in that, It has a layered structure with alternating hard and soft layers, there are gaps between the layers, and the thickness of each layer is 10 - 50 μm.

2. The high-strength plastic laminated molybdenum-rhenium alloy according to claim 1, wherein, Its tensile strength at room temperature is 610 - 700 MPa, and the elongation is 18 - 23%; the tensile strength at 1000 °C is 420 - 450 MPa, and the elongation is 15 - 25%.

3. A preparation process of a high-strength and high-plasticity laminated molybdenum-rhenium alloy, characterized in that, It includes the following steps: (1) Place Mo powder, Re powder, and reinforcing phase powder in a planetary ball mill for uniform mixing to obtain a molybdenum - rhenium composite powder strengthened by a secondary phase; the reinforcing phase is at least one of ZrO2, ZrC, and Ti3AlC2; by weight percentage, Re powder accounts for 5% - 14% of the weight of the mixed powder, the reinforcing phase accounts for 0.5% - 3% of the weight of the mixed powder, and the rest is molybdenum powder. The mixed powder refers to the mixed powder of Mo powder, Re powder, and reinforcing phase powder; (2) Remove impurities from the molybdenum - rhenium composite powder obtained in step (1) in a hydrogen atmosphere to obtain a molybdenum - rhenium alloy composite powder; (3) Subject the molybdenum - rhenium alloy composite powder obtained in step (2) to cold isostatic pressing, pressureless sintering in a hydrogen atmosphere, and hot isostatic pressing in sequence to obtain a secondary - phase - strengthened fine - grained molybdenum - rhenium alloy; (4) Perform cyclic hot rolling and annealing on the secondary - phase - strengthened fine - grained molybdenum - rhenium alloy obtained in step (3), introduce a layered structure through hot large - deformation rolling, and prepare a layered molybdenum - rhenium alloy plate; the billet - opening temperature for hot large - deformation rolling is 1350 - 1450 °C, one - fire one - pass, the single - pass deformation amount is 30 - 35%, and the total deformation amount > 85%; (5) Anneal the layered molybdenum - rhenium alloy plate obtained in step (4) in a hydrogen atmosphere to induce the formation of a high - strength and high - plasticity layered molybdenum - rhenium alloy with alternating hard and soft layers.

4. The preparation process of the high-strength plastic laminated molybdenum-rhenium alloy according to claim 3, characterized in that, In step (1), the rotation speed of the planetary ball mill is 170 - 200 r / min, the mixing time is 3 - 5 h, and the ball - to - material ratio is 10:

1.

5. The preparation process of the high-strength plastic laminated molybdenum-rhenium alloy according to claim 3, characterized in that, In step (1), the average particle size of Mo powder is 2 - 3 μm, the average particle size of Re powder is 6 - 10 μm, and the size of the reinforcing phase is 50 - 200 nm.

6. The preparation process of the high-strength and high-plasticity laminated molybdenum-rhenium alloy with soft and hard phases as described in claim 3, characterized in that In step (2), the temperature for impurity removal is 850 - 900 °C, the hydrogen flow rate is 30 - 35 m 3 / h, and the heat preservation time is 1 - 2 h.

7. The preparation process of the high-strength and plastic laminated molybdenum-rhenium alloy according to claim 3, characterized in that, In step (3), the cold isostatic pressing green compact uses a cold isostatic press, with a pressure of 160 - 200 MPa and a pressure holding time of 20 - 30 min; the pressureless sintering uses a pressureless intermediate frequency furnace and introduces hydrogen. The sintering temperature is 1500 - 1700 °C, the heat preservation time is 2 - 5 h, and the hydrogen flow rate is 6 - 8 m 3 / h; argon is selected for protection during the hot isostatic pressing sintering process. The sintering temperature is 1700 - 1900 °C, the pressure is 170 - 190 MPa, and the heat preservation time is 1 - 2 h.

8. The preparation process of the high-strength plastic laminated molybdenum-rhenium alloy according to claim 7, characterized in that, The obtained secondary - phase - strengthened fine - grained molybdenum - rhenium alloy has a relative density greater than 99%, an average grain size of 15 - 30 μm, and the impurity oxygen element content is less than 16 ppm.

9. The preparation process of the high-strength and plastic laminated molybdenum-rhenium alloy according to claim 3, characterized in that, In step (5), the annealing temperature is 1200 - 1300 °C, and the holding time is 1 h.

10. The preparation process of the high-strength and high-plasticity laminated molybdenum-rhenium alloy according to any one of claims 3 to 9, characterized in that, The obtained high - strength and high - plasticity layered molybdenum - rhenium alloy has a layered structure with alternating hard and soft layers, there are gaps between the layers, and the thickness of each layer is 10 - 50 μm; Its tensile strength at room temperature is 610 - 700 MPa, and the elongation is 18 - 23%; the tensile strength at 1000 °C is 420 - 450 MPa, and the elongation is 15 - 25%.

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