Low-temperature-resistant high-entropy alloy wire and additive manufacturing method thereof

Abstract

The invention discloses a low-temperature-resistant high-entropy alloy wire and an additive manufacturing method thereof, belongs to the technical field of metal materials, and aims to solve the technical problem that the low-temperature toughness of a high-entropy alloy wire and an additive component thereof in the prior art needs to be further improved. Porous nanometer yttrium oxide and a surfactant modified in-situ titanium carbide / graphene hybrid reinforcement phase are synthesized and mixed to prepare a flux core, the flux core is coated with a 304 stainless steel band, multi-pass drawing annealing is conducted, and the composite wire is prepared, so that the problem that high-entropy alloy is difficult to machine is solved, then laser in-situ metallurgy is used for driving skin-core components to be homogenized, and the high-entropy alloy is obtained. And in cooperation with heterogeneous nucleation of a reinforcing phase, a high-entropy alloy component with high compactness and excellent low-temperature toughness is obtained.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, specifically to a low-temperature resistant high-entropy alloy wire and its additive manufacturing method. Background Technology

[0002] High-entropy alloys, due to their unique high-entropy effect and lattice distortion effect, can maintain extremely high fracture toughness and excellent strength-plasticity matching at extremely low temperatures, and are regarded as ideal materials for components serving in cryogenic environments. With the development of additive manufacturing technology, compared with powder bed melting technology, laser-directed energy deposition technology based on wire has gradually become an important way to prepare high-entropy alloy cryogenic components due to its advantages such as high material utilization, fast deposition rate and more suitable for forming large-size components. However, the preparation of high-entropy alloy wire is a prerequisite for realizing this process. At present, the industry is still in the exploratory stage on how to obtain high-entropy alloy wire with both high compositional uniformity and excellent printability.

[0003] In traditional preparation techniques, in order to further improve the strength of alloys at low temperatures, the external method is often used, that is, commercial metal powders are directly mechanically mixed and then composite materials are prepared through powder metallurgy. Although this reinforcement method improves the hardness of the material to a certain extent, it still exposes many insurmountable process defects when facing the stringent requirements of the uniformity of the microstructure of the material in extreme low temperature environments.

[0004] Currently, adding ceramic particles can improve the toughness of alloys. However, commercially available ceramic particles are usually solid and dense structures with extremely high surface energy. During preparation and laser melting, spontaneous agglomeration of particles is very likely to occur, making it difficult to achieve monodispersity in the molten pool. In addition, there is a natural density difference and wettability barrier between them and the molten metal. Simple mechanical mixing lacks a chemically bonded interface, and they are easily disintegrated in the intense thermal convection of laser additive manufacturing, causing debonding of the reinforcing phase interface. This makes it difficult for existing high-entropy alloy wires and their reinforced high-entropy alloy components to maintain both high strength and high toughness when operating at low temperatures. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature resistant high-entropy alloy wire and its additive manufacturing method, which solves the technical problem that the low-temperature toughness of high-entropy alloy wires and their additive components in the prior art needs to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a low-temperature resistant high-entropy alloy wire, wherein the high-entropy alloy wire comprises a metal sheath and a core powder; wherein the metal sheath is a 304 stainless steel strip, and the core powder comprises the following components by weight: 90-95 parts alloy powder, 0.1-0.5 parts rare earth oxide powder, 1-5 parts nano-hybrid reinforcing phase, and 0.2-0.5 parts ferrosilicon powder; The rare earth oxide powder is prepared by the following steps: A1. Yttrium nitrate hexahydrate, trimesic acid, N,N-dimethylformamide and ethanol are placed in a reaction vessel and stirred at room temperature for 0.5-1 h. The reaction is carried out in a solvothermal manner for 10-12 h. The metal-organic framework precursor is obtained after post-treatment. A2. Add the metal-organic framework precursor to a muffle furnace and heat it to 600-700℃ at a heating rate of 2-5℃ / min. Hold it at this temperature for 2-4 hours and then grind it through a 200-mesh sieve after cooling to obtain porous nano-yttrium oxide.

[0007] Further, in step A1, the ratio of yttrium nitrate hexahydrate, trimesic acid, N,N-dimethylformamide, and ethanol is 1.5-2.5g:1-2g:30-50mL:30-50mL. The solvothermal reaction operation includes: transferring the reaction solution, which has been stirred at room temperature, to a reaction vessel lined with polytetrafluoroethylene, and carrying out a solvothermal reaction at 100-120℃ for 10-12 hours, followed by post-treatment to obtain the metal-organic framework precursor.

[0008] Furthermore, in step A1, the post-processing step includes: after the reaction is completed, wait for the reaction to cool to room temperature, filter, and wash the filter cake with ethanol 2-4 times to obtain the metal-organic framework precursor.

[0009] Furthermore, the alloy powder comprises the following components in parts by weight: 30-40 parts cobalt powder, 10-20 parts nickel powder, 1-5 parts iron powder, 1-5 parts chromium powder, and 30-40 parts manganese powder, with a core powder filling rate of 23-28%.

[0010] Furthermore, the particle size of the cobalt powder, nickel powder, iron powder, chromium powder, and manganese powder is 15-45 μm.

[0011] Furthermore, the nano-hybridized reinforcing phase is prepared by the following steps: B1. Place graphene oxide and deionized water in a reaction vessel and stir. Add hexadecyltrimethylammonium bromide aqueous solution. Heat the reaction vessel to 55-65℃ and keep it at that temperature for 1-2 hours. Post-process to obtain intercalated modified graphene oxide. B2. Intercalated graphene oxide, ethanol and ethylene glycol were placed in a reaction vessel and stirred. Tetrabutyl titanate was added. After hydrothermal reaction for 8-10 hours, the titanium grafted composite precursor was obtained through post-treatment. B3. The titanium grafted composite precursor was placed in a tube furnace under argon atmosphere protection, heated to 1250-1350℃ at 5℃ / min, held for 2 hours, and then ground through a 200-mesh sieve to obtain the nano-hybridized reinforcing phase.

[0012] Further, in step B1, the ratio of graphene oxide, deionized water, and hexadecyltrimethylammonium bromide aqueous solution is 1-2g:800-1200mL:100-150mL. The hexadecyltrimethylammonium bromide aqueous solution is obtained by uniformly mixing hexadecyltrimethylammonium bromide and deionized water at a ratio of 1g:250mL. The post-processing steps include: after the reaction is completed, the reaction is allowed to cool to room temperature, filtered, the filter cake is washed with ethanol 1-3 times, transferred to an oven at a temperature of 50-60℃, and dried to constant weight to obtain intercalated modified graphene oxide.

[0013] Further, in step B2, the ratio of the intercalated modified graphene oxide, ethanol, ethylene glycol, and tetrabutyl titanate is 2-4g:150-200mL:150-200mL:18-20mL. The hydrothermal reaction operation steps include: after adding tetrabutyl titanate, transferring the reaction solution to a polytetrafluoroethylene-lined stainless steel high-pressure reactor and sealing it, and carrying out a solvothermal reaction at 150-160℃ for 8-10 hours, followed by post-treatment to obtain the titanium grafted composite precursor.

[0014] Further, in step B2, the post-processing step includes: after the reaction is completed, wait for the reaction system to cool to room temperature, add 2.5-3.5 mL of glacial acetic acid and 8-10 mL of 0.4-0.6 mol / L glucose aqueous solution, stir at room temperature for 1-2 h, filter, wash the filter cake with deionized water 1-3 times, transfer it to a freeze dryer at -60℃, freeze dry for 10-12 h to obtain the titanium grafted composite precursor.

[0015] One method for preparing a low-temperature resistant high-entropy alloy wire includes the following steps: C1. Place the alloy powder, rare earth oxide powder, nano-hybrid reinforcing phase and ferrosilicon powder in a planetary ball mill under argon atmosphere protection, add stainless steel grinding balls, stir and ball mill for 4-6 hours to obtain core powder. C2. Feed the 304 stainless steel strip into the rolling mill, use the forming rolls to roll the strip into a U-shaped groove, fill the U-shaped groove with the core powder evenly, and roll the U-shaped groove into an O-shaped tube by the closing rolls to obtain the core alloy wire blank. C3. The flux-cored alloy wire blank is rolled, drawn and reduced in diameter, bright annealed and surface mechanically cleaned to obtain a Φ1.6±0.05mm low-temperature high-entropy alloy wire.

[0016] Furthermore, in step C1, the ball-to-material ratio is (5-10):1, and the ball mill speed is 200-300 r / min; in step C2, the thickness of the 304 stainless steel strip is 0.2-0.3 mm, and the width is 8-12 mm; in step C3, the annealing temperature is 1050-1100℃.

[0017] The present invention also proposes a method for additive manufacturing using low-temperature resistant high-entropy alloy wire, comprising the following steps: S1. Fix the polished and cleaned austenitic stainless steel plate on the worktable of the laser fused wire deposition equipment. Add the low-temperature high-entropy alloy wire to the wire feeder in a side-shaft front-mounted manner. Adjust the wire feeding angle to 30-45° so that the tip of the low-temperature high-entropy alloy wire is aligned with the center of the laser spot. S2. Under the protection of argon atmosphere, adjust the laser head to be perpendicular to the substrate surface, set the defocusing amount to 2-6mm, turn on the laser and wire feeder to perform layer-by-layer deposition, and obtain low-temperature resistant high-entropy alloy additive manufacturing components.

[0018] Furthermore, the laser power is 1.0-3.0kW, the scanning speed is 0.3-0.9m / min, the wire feeding speed is 0.8-2m / min, the wire spacing is 0.5-2.0mm, the interlayer cooling temperature is ≤200℃, the laser beam is a circular spot of 2.0-4.0mm, and the protective argon flow rate is 15-25L / min.

[0019] The present invention has the following beneficial effects: The low-temperature high-entropy alloy wire prepared by this invention achieves multi-level synergistic dispersion of the reinforcement in the core system by introducing porous nano-yttrium oxide derived from a metal-organic framework and an in-situ constructed titanium carbide / graphene hybrid reinforcement phase. Among them, the unique porous framework structure of yttrium oxide significantly increases the specific surface area and forms a tight bond with the metal matrix during ball milling through physical intercalation, effectively avoiding the agglomeration problem of traditional nanoparticles. At the same time, the titanium carbide / graphene prepared by surfactant intercalation and in-situ carbothermal reduction improves the wettability of carbon-based materials and metal melts through Ti-C chemical bonding anchoring and interlayer spacing expansion. This not only solves the problem of uneven distribution of a single reinforcement phase, but also improves the chemical stability and dispersion uniformity of the reinforcement phase during subsequent melting, giving the alloy wire excellent low-temperature toughness.

[0020] The low-temperature resistant high-entropy alloy wire prepared by this invention adopts a composite structure in which a 304 stainless steel strip is used as the sheath to cover a powder core with a specific ratio. Through multi-pass deformation heat treatment of the sheath and core components, the strength of the high-entropy alloy is improved. In this structure, the stainless steel sheath with good toughness bears the main plastic deformation load, which drives the powder core to densify and form a mechanical interlock. Combined with the static recrystallization induced by the intermediate annealing process, the internal stress and texture defects caused by severe deformation are eliminated. This ensures the balance between stiffness and flexibility of the wire during long-term continuous wire feeding. Furthermore, by limiting the powder core filling rate and drawing diameter reduction, the residual porosity inside the core wire is significantly reduced, thereby improving the low-temperature toughness of the high-entropy alloy wire.

[0021] The low-temperature high-entropy alloy additive manufacturing component prepared by this invention relies on the in-situ metallurgical reaction and non-equilibrium rapid solidification mechanism during laser-directed energy deposition to achieve atomic-level mixing and homogenization of the skin and core components in a micro-area molten pool, constructing a chemically uniform single-phase face-centered cubic solid solution matrix. In this process, the diffusely distributed high thermal stability nano-hybrid phase and porous oxides act as efficient heterogeneous nucleation points, significantly improving the nucleation rate and pinning grain boundary migration, effectively suppressing the grain coarsening trend during repeated thermal cycling. At the same time, the laser rapid solidification feature suppresses elemental segregation, and combined with the grain refinement strengthening induced by the reinforcing phase, a fine and isotropic equiaxed grain structure is formed inside the component, endowing the component with excellent dislocation slip resistance and plastic deformation ability at extremely low temperatures, and improving its low-temperature strength and toughness. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The graphene oxide used in this invention was purchased from Zhongke Leiming (Beijing) Technology Co., Ltd., with a particle size of 0.5-3μm and a content of ≥99%. The ferrosilicon powder used in this invention was purchased from Sichuan Greenforest Technology Co., Ltd., with the grade FeSi75 and a particle size of 250μm. Example 1

[0024] This embodiment provides a method for preparing rare earth oxide powder, including the following steps: Step I: Preparation of metal-organic framework precursors Weigh out 15g of yttrium nitrate hexahydrate, 10g of trimesic acid, 300mL of N,N-dimethylformamide and 300mL of ethanol and place them in a reaction vessel. Stir at room temperature for 0.5h. Transfer the reaction solution after stirring at room temperature to a reaction vessel with a polytetrafluoroethylene liner and carry out a solvothermal reaction at 100℃ for 10 hours. After the reaction is completed, wait for the reaction to cool to room temperature, filter, and wash the filter cake twice with ethanol to obtain the metal-organic framework precursor.

[0025] Step II: Preparation of porous yttrium oxide nanoparticles The metal-organic framework precursor was added to a muffle furnace and heated to 600°C at a heating rate of 2°C / min. After holding at this temperature for 2 hours, the precursor was cooled and ground through a 200-mesh sieve to obtain porous nano-yttrium oxide.

[0026] Under a solvothermal environment, yttrium ions dissociated from yttrium nitrate hexahydrate act as metal nodes, coordinating and self-assembling with deprotonated carboxyl groups in trimesic acid (an organic ligand). In a mixed solvent of N,N-dimethylformamide / ethanol, a yttrium-based organic framework precursor with a three-dimensional periodic network structure is grown. Subsequently, during the high-temperature calcination of the precursor, the organic framework undergoes pyrolysis and oxidation and escapes in gaseous form. The remaining metal nodes are oxidized and crystallized in situ to form yttrium oxide, effectively preserving the framework morphology of the precursor and forming a rich porous structure due to the removal of organic matter, ultimately yielding porous nano-yttrium oxide.

[0027] The yttrium-based organic framework precursor constructed by solvothermal reaction ensures the chemical composition uniformity of the reinforcing phase through molecular-level self-assembly. Subsequently, the porous nano-yttrium oxide derived by high-temperature calcination, with its retained framework structure and high specific surface area, can greatly improve its physical compatibility and dispersion uniformity in the core powder. In the high-temperature rapid cooling molten pool of laser additive manufacturing, this dispersed nanoporous oxide, as a highly efficient heterogeneous nucleation point, can significantly pin grain boundaries and hinder grain coarsening, thereby endowing high-entropy alloy components with excellent low-temperature strength and toughness through a fine-grain strengthening mechanism. Example 2

[0028] This embodiment provides a method for preparing rare earth oxide powder, including the following steps: Step I: Preparation of metal-organic framework precursors Weigh out 20g of yttrium nitrate hexahydrate, 15g of trimesic acid, 400mL of N,N-dimethylformamide and 400mL of ethanol and place them in a reaction vessel. Stir at room temperature for 1 hour. Transfer the reaction solution to a reaction vessel with a polytetrafluoroethylene liner and carry out a solvothermal reaction at 110℃ for 11 hours. After the reaction is completed, wait for the reaction to cool to room temperature, filter, and wash the filter cake three times with ethanol to obtain the metal-organic framework precursor.

[0029] Step II: Preparation of porous yttrium oxide nanoparticles The metal-organic framework precursor was added to a muffle furnace and heated to 650°C at a heating rate of 4°C / min. After holding at this temperature for 3 hours, the precursor was cooled and ground through a 200-mesh sieve to obtain porous nano-yttrium oxide. Example 3

[0030] This embodiment provides a method for preparing rare earth oxide powder, including the following steps: Step I: Preparation of metal-organic framework precursors Weigh out 25g of yttrium nitrate hexahydrate, 20g of trimesic acid, 500mL of N,N-dimethylformamide and 500mL of ethanol and place them in a reaction vessel. Stir at room temperature for 1 hour. Transfer the reaction solution to a reaction vessel with a polytetrafluoroethylene liner and carry out a solvothermal reaction at 120℃ for 12 hours. After the reaction is completed, wait for the reaction to cool to room temperature, filter, and wash the filter cake with ethanol 4 times to obtain the metal-organic framework precursor.

[0031] Step II: Preparation of porous yttrium oxide nanoparticles The metal-organic framework precursor was added to a muffle furnace and heated to 700°C at a heating rate of 5°C / min. After holding at this temperature for 4 hours, the precursor was cooled and ground through a 200-mesh sieve to obtain porous nano-yttrium oxide. Example 4

[0032] This embodiment provides a method for preparing a nano-hybridized reinforcing phase, including the following steps: Step ①: Preparation of intercalated modified graphene oxide Mix hexadecyltrimethylammonium bromide and deionized water at a ratio of 1g:250mL to obtain an aqueous solution of hexadecyltrimethylammonium bromide for later use. Weigh 10g of graphene oxide and 8000mL of deionized water and place them in a reaction vessel and stir. Add 1000mL of hexadecyltrimethylammonium bromide aqueous solution, heat the reaction vessel to 55℃, and keep it at that temperature for 1h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake once with ethanol, transfer it to an oven at 50℃, and dry it to constant weight to obtain intercalated modified graphene oxide.

[0033] Step 2: Preparation of titanium-grafted composite precursor Weigh out 20g of intercalated graphene oxide, 1500mL of ethanol and 1500mL of ethylene glycol and place them in a reaction vessel and stir. Add 180mL of tetrabutyl titanate and transfer the reaction solution to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and seal it. Perform a solvothermal reaction at 160℃ for 8 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, add 25mL of glacial acetic acid and 80mL of 0.4mol / L glucose aqueous solution, stir at room temperature for 1 hour, filter, wash the filter cake once with deionized water, transfer it to a freeze dryer at -60℃ and freeze dry for 10 hours to obtain the titanium grafted composite precursor.

[0034] Step ③: Preparation of nano-hybridized reinforcing phase The titanium-grafted composite precursor was placed in a tube furnace under argon atmosphere protection, heated to 1250℃ at 5℃ / min, held at that temperature for 2 hours, and then ground through a 200-mesh sieve to obtain the nano-hybridized reinforcing phase.

[0035] By utilizing the electrostatic interaction and ion exchange between the cationic surfactant hexadecyltrimethylammonium bromide and the oxygen-containing functional groups on the surface of graphene oxide, the interlayer spacing of graphene oxide is expanded and the surface is organically modified. Subsequently, in a solvothermal system, tetrabutyl titanate undergoes hydrolysis and condensation, and the resulting titanium source precursor, along with glucose as an auxiliary carbon source, achieves in-situ anchoring and coating on the expanded structure and surface of the modified graphene oxide. Finally, an in-situ carbothermal reduction reaction is initiated under a high-temperature inert atmosphere, and the active carbon atoms generated by the graphene framework, residual organic matter, and glucose pyrolysis are used to reduce and carbonize the titanium oxide, ultimately forming a titanium carbide nano-hybrid reinforcing phase in-situ supported on the graphene matrix.

[0036] By utilizing the layer-expansion modification effect of surfactants, the recombination of graphene sheets in subsequent processing is effectively suppressed, ensuring the high dispersion of the two-dimensional matrix within the sheath powder. Subsequently, through precursor anchoring with a titanium source and in-situ carbothermal reduction, a titanium carbide / graphene heterostructure with strong interfacial bonding and good wettability is constructed, solving the problem of poor compatibility between pure carbon materials and metal matrices. In the fast solidification molten pool of laser additive manufacturing, this highly thermally stable nano-hybrid phase acts as a dispersed pinning point and nucleation center, which can significantly refine the high-entropy alloy grains and hinder dislocation slip, thereby endowing the formed component with excellent low-temperature strength and toughness. Example 5

[0037] This embodiment provides a method for preparing a nano-hybridized reinforcing phase, including the following steps: Step ①: Preparation of intercalated modified graphene oxide Mix hexadecyltrimethylammonium bromide and deionized water at a ratio of 1g:250mL to obtain an aqueous solution of hexadecyltrimethylammonium bromide for later use. Weigh 15g of graphene oxide and 10000mL of deionized water and place them in a reaction vessel and stir. Add 1250mL of hexadecyltrimethylammonium bromide aqueous solution, heat the reaction vessel to 60℃, and keep it at this temperature for 1.5h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake twice with ethanol, transfer it to an oven at 55℃, and dry it to constant weight to obtain intercalated modified graphene oxide.

[0038] Step 2: Preparation of titanium-grafted composite precursor Weigh out 30g of intercalated graphene oxide, 1750mL of ethanol and 1750mL of ethylene glycol and place them in a reaction vessel and stir. Add 190mL of tetrabutyl titanate and transfer the reaction solution to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and seal it. Perform a solvothermal reaction at 155℃ for 9 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, add 30mL of glacial acetic acid and 90mL of 0.5mol / L glucose aqueous solution, stir at room temperature for 1.5h, filter, wash the filter cake twice with deionized water, transfer it to a freeze dryer at -60℃ and freeze dry for 11h to obtain the titanium grafted composite precursor.

[0039] Step ③: Preparation of nano-hybridized reinforcing phase The titanium-grafted composite precursor was placed in a tube furnace under argon atmosphere protection, heated to 1300℃ at 5℃ / min, held at that temperature for 2 hours, and then ground through a 200-mesh sieve to obtain the nano-hybridized reinforcing phase. Example 6

[0040] This embodiment provides a method for preparing a nano-hybridized reinforcing phase, including the following steps: Step ①: Preparation of intercalated modified graphene oxide Mix hexadecyltrimethylammonium bromide and deionized water at a ratio of 1g:250mL to obtain an aqueous solution of hexadecyltrimethylammonium bromide for later use. Weigh 20g of graphene oxide and 12000mL of deionized water and place them in a reaction vessel and stir. Add 1500mL of hexadecyltrimethylammonium bromide aqueous solution, heat the reaction vessel to 65℃, and keep it at this temperature for 2 hours. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake three times with ethanol, transfer it to an oven at 60℃, and dry it to constant weight to obtain intercalated modified graphene oxide.

[0041] Step 2: Preparation of titanium-grafted composite precursor Weigh out 40g of intercalated graphene oxide, 2000mL of ethanol and 2000mL of ethylene glycol and place them in a reaction vessel and stir. Add 20mL of tetrabutyl titanate and transfer the reaction solution to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and seal it. Perform a solvothermal reaction at 160℃ for 10 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, add 35mL of glacial acetic acid and 100mL of 0.6mol / L glucose aqueous solution, stir at room temperature for 2 hours, filter, wash the filter cake three times with deionized water, transfer it to a freeze dryer at -60℃ and freeze dry for 12 hours to obtain the titanium grafted composite precursor.

[0042] Step ③: Preparation of nano-hybridized reinforcing phase The titanium-grafted composite precursor was placed in a tube furnace under argon atmosphere protection, heated to 1350℃ at 5℃ / min, held at that temperature for 2 hours, and then ground through a 200-mesh sieve to obtain the nano-hybridized reinforcing phase. Example 7

[0043] This embodiment provides a method for preparing a low-temperature resistant high-entropy alloy wire, including the following steps: Step 1: Preparation of core powder Weigh out the following components by weight: 30 parts cobalt powder, 10 parts nickel powder, 1 part iron powder, 1 part chromium powder, and 30 parts manganese powder, and mix them to obtain alloy powder. Weigh out 95 parts by weight of alloy powder, 0.1 parts by weight of rare earth oxide powder, 1 part by weight of nano-hybrid reinforcing phase and 0.2 parts by weight of ferrosilicon powder and place them in a planetary ball mill under argon atmosphere protection. Add stainless steel grinding balls at a ball-to-material ratio of 5:1 and stir and ball mill at a rate of 200 r / min for 4 hours to obtain core powder.

[0044] Step 2: Preparation of flux-cored alloy wire blank A 304 stainless steel strip with a thickness of 0.2 mm and a width of 8 mm is fed into a rolling mill. The strip is rolled into a U-shaped groove using forming rolls. The core powder is then evenly filled into the U-shaped groove with a filling rate of 23%. The U-shaped groove is rolled into an O-shaped tube by closing rolls to obtain the core alloy wire blank.

[0045] Step 3: Preparation of low-temperature resistant high-entropy alloy wire The flux-cored alloy wire blank is rolled, drawn to reduce diameter, bright annealed at 1050℃, and surface mechanically cleaned to obtain a Φ1.55mm low-temperature high-entropy alloy wire.

[0046] By utilizing the strong impact and shearing action of high-energy ball milling, the mechanical mixing and fine dispersion of multi-component metal powder and nano-reinforcing phase are achieved. Subsequently, 304 stainless steel strip rich in iron, chromium and nickel elements is used as the skin to coat the alloy powder core rich in cobalt, manganese and nickel elements. Through multiple rolling and drawing deformation, the powder core is densified and forms a tight mechanical bond with the skin. Combined with high-temperature annealing to induce static recrystallization of the metal matrix and eliminate work hardening, a high-entropy alloy wire with a specific skin-core structure is finally obtained.

[0047] High-energy ball milling ensures the dispersed distribution of trace nano-hybrid phases in the core matrix through mechanochemical action, effectively avoiding agglomeration and providing a uniform, dispersed, and reinforced foundation for the formed components. A composite structure with a specific ratio of powder core wrapped in 304 steel strip is used. High-density drawing combined with annealing treatment eliminates internal pores in the powder core and significantly reduces the porosity of the weld, while giving the filament suitable rigidity and ductility, ensuring the stability of long-term continuous filament feeding and the density of the internal structure of the low-temperature components. Example 8

[0048] This embodiment provides a method for preparing a low-temperature resistant high-entropy alloy wire, including the following steps: Step 1: Preparation of core powder Weigh out the following by weight: 40 parts cobalt powder, 20 parts nickel powder, 1 part iron powder, 1 part chromium powder and 40 parts manganese powder, and mix them to obtain alloy powder. Weigh out 92 parts by weight of alloy powder, 0.3 parts by weight of rare earth oxide powder, 3 parts by weight of nano-hybrid reinforcing phase and 0.4 parts by weight of ferrosilicon powder and place them in a planetary ball mill under argon atmosphere protection. Add stainless steel grinding balls at a ball-to-material ratio of 7:1 and stir and ball mill at a rate of 250 r / min for 5 hours to obtain core powder.

[0049] Step 2: Preparation of flux-cored alloy wire blank A 304 stainless steel strip with a thickness of 0.25 mm and a width of 10 mm is fed into the rolling mill. The strip is rolled into a U-shaped groove using forming rolls. The core powder is then evenly filled into the U-shaped groove with a filling rate of 25%. The U-shaped groove is rolled into an O-shaped tube by closing rolls to obtain the core alloy wire blank.

[0050] Step 3: Preparation of low-temperature resistant high-entropy alloy wire The flux-cored alloy wire blank is rolled, drawn to reduce diameter, bright annealed at 1075℃, and surface mechanically cleaned to obtain a Φ1.6mm low-temperature high-entropy alloy wire. Example 9

[0051] This embodiment provides a method for preparing a low-temperature resistant high-entropy alloy wire, including the following steps: Step 1: Preparation of core powder Weigh out the following components by weight: 40 parts cobalt powder, 20 parts nickel powder, 5 parts iron powder, 5 parts chromium powder, and 40 parts manganese powder, and mix them to obtain alloy powder. Weigh out 90 parts by weight of alloy powder, 0.5 parts by weight of rare earth oxide powder, 5 parts by weight of nano-hybrid reinforcing phase and 0.5 parts by weight of ferrosilicon powder and place them in a planetary ball mill under argon atmosphere protection. Add stainless steel grinding balls at a ball-to-material ratio of 10:1 and stir and ball mill at a rate of 300 r / min for 6 hours to obtain core powder.

[0052] Step 2: Preparation of flux-cored alloy wire blank A 304 stainless steel strip with a thickness of 0.3 mm and a width of 12 mm is fed into the rolling mill. The strip is rolled into a U-shaped groove using forming rolls. The core powder is then evenly filled into the U-shaped groove with a filling rate of 28%. The U-shaped groove is rolled into an O-shaped tube by closing rolls to obtain the core alloy wire blank.

[0053] Step 3: Preparation of low-temperature resistant high-entropy alloy wire The flux-cored alloy wire blank is rolled, drawn to reduce diameter, bright annealed at 1100℃, and surface mechanically cleaned to obtain a Φ1.65mm low-temperature high-entropy alloy wire. Example 10

[0054] This embodiment provides an additive manufacturing method for low-temperature resistant high-entropy alloy wire, including the following steps: After grinding and cleaning, the austenitic stainless steel plate is fixed on the worktable of the laser fused wire deposition equipment. The low-temperature high-entropy alloy wire is fed into the wire feeder in a side-shaft front manner. The wire feeding angle is adjusted to 30° so that the tip of the low-temperature high-entropy alloy wire is aligned with the center of the laser spot. Under the protection of argon atmosphere, the laser head is adjusted to be perpendicular to the substrate surface, the defocusing amount is set to 2mm, and the laser and wire feeder are turned on to perform layer-by-layer deposition to obtain low-temperature high-entropy alloy additive manufacturing components. The laser power is 1.0kW, the scanning speed is 0.3m / min, the wire feeding speed is 0.8m / min, the wire spacing is 0.5mm, the interlayer cooling temperature is 100℃, the laser beam is a 2.0mm circular spot, and the protective argon flow rate is 15L / min.

[0055] Under the irradiation of a high-energy-density laser beam, the surface of the austenitic stainless steel substrate and the continuously fed flux-cored composite wire melt synchronously to form a micro-melt pool. Utilizing the intense convection and thermal diffusion within the molten pool, in-situ metallurgical melting and element redistribution are induced between the outer stainless steel sheath and the inner alloy powder core components of the wire. In the liquid phase, the transformation from a mechanical composite structure to a chemically homogeneous high-entropy alloy solid solution is completed. Subsequently, under argon protection and interlayer thermal control, the melt undergoes a non-equilibrium rapid solidification process, relying on the grains of the substrate or the previous deposition layer for epitaxial growth and layer-by-layer stacking, thereby realizing the solid forming of the metal component.

[0056] Laser in-situ metallurgy utilizes the strong convection of the molten pool to drive the rapid homogenization of stainless steel sheet and alloy powder core in the liquid phase, eliminating macroscopic segregation and ensuring the formation of a stable single-phase face-centered cubic solid solution. The non-equilibrium rapid solidification process, combined with the previously introduced nano-hybrid enhancement, suppresses grain growth and stimulates heterogeneous nucleation through high supercooling, constructing a fine and uniform crystal structure. This significantly improves the low-temperature strength and toughness ratio of the material. The strict atmosphere protection and interlayer thermal control stacking effectively curb the generation of oxidation pores and hot cracks, ensuring the reliability of the formed components in cryogenic service on a high-density basis. Example 11

[0057] This embodiment provides an additive manufacturing method for low-temperature resistant high-entropy alloy wire, including the following steps: After grinding and cleaning, the austenitic stainless steel plate is fixed on the worktable of the laser fused wire deposition equipment. The low-temperature high-entropy alloy wire is fed into the wire feeder in a side-shaft front manner. The wire feeding angle is adjusted to 35° so that the tip of the low-temperature high-entropy alloy wire is aligned with the center of the laser spot. Under the protection of argon atmosphere, the laser head is adjusted to be perpendicular to the substrate surface, the defocusing amount is set to 4mm, and the laser and wire feeder are turned on to perform layer-by-layer deposition to obtain low-temperature high-entropy alloy additive manufacturing components. The laser power is 2.0kW, the scanning speed is 0.6m / min, the wire feeding speed is 1.5m / min, the wire spacing is 1.5mm, the interlayer cooling temperature is 150℃, the laser beam is a 3.0mm circular spot, and the protective argon flow rate is 20L / min. Example 12

[0058] This embodiment provides an additive manufacturing method for low-temperature resistant high-entropy alloy wire, including the following steps: After grinding and cleaning, the austenitic stainless steel plate is fixed on the worktable of the laser fused wire deposition equipment. The low-temperature high-entropy alloy wire is fed into the wire feeder in a side-shaft front manner. The wire feeding angle is adjusted to 45° so that the tip of the low-temperature high-entropy alloy wire is aligned with the center of the laser spot. Under the protection of argon atmosphere, the laser head is adjusted to be perpendicular to the substrate surface, the defocusing amount is set to 6mm, and the laser and wire feeder are turned on to perform layer-by-layer deposition to obtain low-temperature high-entropy alloy additive manufacturing components. The laser power is 3.0kW, the scanning speed is 0.9m / min, the wire feeding speed is 2m / min, the wire spacing is 2.0mm, the interlayer cooling temperature is 180℃, the laser beam is a 4.0mm circular spot, and the protective argon flow rate is 25L / min.

[0059] Comparative Example 1 The difference between this comparative example and Examples 9 and 12 is that rare earth oxide powder is omitted when preparing the core powder in step (1).

[0060] Comparative Example 2 The difference between this comparative example and Examples 9 and 12 is that the nano-hybrid reinforcing phase was omitted when preparing the core powder in step (1).

[0061] Performance testing: The low-temperature tensile toughness of the low-temperature high-entropy alloy wires prepared in Examples 7-9 and Comparative Examples 1-3, as well as the low-temperature high-entropy alloy additive manufacturing components prepared in Examples 10-12 and Comparative Examples 1-3, was tested at -196°C in accordance with the standard GB / T 228.3-2019 "Metallic materials, tensile testing - Part 3: Low-temperature testing method". The low-temperature tensile toughness of the specimens was characterized by elongation after fracture and cross-sectional area shrinkage. The low-temperature impact toughness of the low-temperature high-entropy alloy wires prepared in Examples 7-9 and Comparative Examples 1-3, as well as the low-temperature high-entropy alloy additive manufacturing components prepared in Examples 10-12 and Comparative Examples 1-3, was tested at -196°C in accordance with the standard GB / T 229-2020 "Charpy Pendulum Impact Test Method for Metallic Materials". The low-temperature impact toughness of the specimens was characterized by the impact absorption energy consumed when the specimens were broken by pendulum impact. The hardness of the low-temperature high-entropy alloy wires prepared in Examples 7-9 and Comparative Examples 1-3, as well as the low-temperature high-entropy alloy additive manufacturing components prepared in Examples 10-12 and Comparative Examples 1-3, was tested at -196°C in accordance with the standard GB / T 4340.1-2024 "Metallic materials - Vickers hardness test - Part 1: Test method". The hardness of the samples was characterized by Vickers hardness. The specific data are shown in Table 1-2.

[0062] Table 1 - Performance Test Data of Various High Entropy Alloy Wire Samples Table 2 - Performance test data of various high-entropy alloy additive manufacturing component samples Data Analysis: A comparative analysis of the data in the above tables reveals that the low-temperature high-entropy alloy wire prepared by this invention exhibits an elongation at break of 14.5% and a cross-sectional area shrinkage of 18.1% at -196°C, with an impact absorption energy of 30.5 J and a Vickers hardness of 285 HV. The low-temperature high-entropy alloy additive manufacturing component made from this low-temperature high-entropy alloy wire exhibits an elongation at break of 15.5% and a cross-sectional area shrinkage of 20.9% at -196°C, with an impact absorption energy of 36.8 J and a Vickers hardness of 290 HV. All these data are superior to the comparative example.

[0063] This invention first synthesizes porous nano-yttrium oxide and a surfactant-modified in-situ titanium carbide / graphene hybrid reinforcing phase, mixes them to prepare a core, and then uses 304 stainless steel strip to coat the core and undergo multiple drawing and annealing processes to obtain a composite wire, thus solving the problem of difficult processing of high-entropy alloys. Finally, laser in-situ metallurgy is used to drive the homogenization of the core and skin components, combined with the heterogeneous nucleation of the reinforcing phase, to obtain a high-entropy alloy component with high density and excellent low-temperature toughness.

[0064] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0065] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0066] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-temperature resistant, high-entropy alloy wire, characterized in that, The high-entropy alloy wire comprises a metal sheath and a core powder; wherein the metal sheath is a 304 stainless steel strip, and the core powder comprises the following components by weight: 90-95 parts alloy powder, 0.1-0.5 parts rare earth oxide powder, 1-5 parts nano-hybrid reinforcing phase, and 0.2-0.5 parts ferrosilicon powder; The rare earth oxide powder is prepared by the following steps: A1. Yttrium nitrate hexahydrate, trimesic acid, N,N-dimethylformamide and ethanol are placed in a reaction vessel and stirred at room temperature for 0.5-1 h. The reaction is carried out in a solvothermal manner for 10-12 h. The metal-organic framework precursor is obtained after post-treatment. A2. Add the metal-organic framework precursor to a muffle furnace and heat it to 600-700℃ at a heating rate of 2-5℃ / min. Hold it at this temperature for 2-4 hours and then grind it through a 200-mesh sieve after cooling to obtain porous nano-yttrium oxide.

2. The low-temperature resistant high-entropy alloy wire according to claim 1, characterized in that, In step A1, the ratio of yttrium nitrate hexahydrate, trimesic acid, N,N-dimethylformamide and ethanol is 1.5-2.5g:1-2g:30-50mL:30-50mL.

3. The low-temperature resistant high-entropy alloy wire according to claim 1, characterized in that, The alloy powder comprises the following components in parts by weight: 30-40 parts cobalt powder, 10-20 parts nickel powder, 1-5 parts iron powder, 1-5 parts chromium powder, and 30-40 parts manganese powder, with a core powder filling rate of 23-28%.

4. The low-temperature resistant high-entropy alloy wire according to claim 1, characterized in that, The nano-hybridized reinforcing phase is prepared by the following steps: B1. Place graphene oxide and deionized water in a reaction vessel and stir. Add hexadecyltrimethylammonium bromide aqueous solution. Heat the reaction vessel to 55-65℃ and keep it at that temperature for 1-2 hours. Post-process to obtain intercalated modified graphene oxide. B2. Intercalated graphene oxide, ethanol and ethylene glycol were placed in a reaction vessel and stirred. Tetrabutyl titanate was added. After hydrothermal reaction for 8-10 hours, the titanium grafted composite precursor was obtained through post-treatment. B3. The titanium grafted composite precursor was placed in a tube furnace under argon atmosphere protection, heated to 1250-1350℃ at 5℃ / min, held for 2 hours, and then ground through a 200-mesh sieve to obtain the nano-hybridized reinforcing phase.

5. The low-temperature resistant high-entropy alloy wire according to claim 4, characterized in that, In step B1, the ratio of the amount of graphene oxide, deionized water and hexadecyltrimethylammonium bromide aqueous solution is 1-2g:800-1200mL:100-150mL. The hexadecyltrimethylammonium bromide aqueous solution is obtained by mixing hexadecyltrimethylammonium bromide and deionized water at a ratio of 1g:250mL.

6. The low-temperature resistant high-entropy alloy wire according to claim 4, characterized in that, In step B2, the ratio of the intercalated modified graphene oxide, ethanol, ethylene glycol and tetrabutyl titanate is 2-4g:150-200mL:150-200mL:18-20mL.

7. A method for additive manufacturing using low-temperature resistant high-entropy alloy wire as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Fix the polished and cleaned austenitic stainless steel plate on the worktable of the laser fused wire deposition equipment. Add the low-temperature high-entropy alloy wire to the wire feeder in a side-shaft front-mounted manner. Adjust the wire feeding angle to 30-45° so that the tip of the low-temperature high-entropy alloy wire is aligned with the center of the laser spot. S2. Under the protection of argon atmosphere, adjust the laser head to be perpendicular to the substrate surface, set the defocusing amount to 2-6mm, turn on the laser and wire feeder to perform layer-by-layer deposition, and obtain low-temperature resistant high-entropy alloy additive manufacturing components.

8. The additive manufacturing method for low-temperature resistant high-entropy alloy wire according to claim 7, characterized in that, The laser power is 1.0-3.0kW, the scanning speed is 0.3-0.9m / min, the wire feeding speed is 0.8-2m / min, the wire spacing is 0.5-2.0mm, the interlayer cooling temperature is ≤200℃, the laser beam is a circular spot of 2.0-4.0mm, and the protective argon flow rate is 15-25L / min.

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