A method of in-situ generation of Ti-containing high-entropy alloys by laser degradation melting additive manufacturing

Abstract

This invention discloses a method for in-situ generation of Ti-containing high-entropy alloys using laser-based degraded melting additive manufacturing. The method involves preparing titanium alloy composite powders with varying high-entropy alloy contents using a planetary ball mill. The composite powders are then fed into a laser additive manufacturing powder feeding system, where a low-heat-input laser is used for layer-by-layer melting and deposition. The process is paused after each layer is completed, and the formed layer is scanned with 2-4 laser scans using progressively decreasing heat inputs. This process alternates between deposition and multi-stage degraded laser scanning until the entire layer is formed. This invention allows for in-situ performance optimization during the forming process and is compatible with various additive manufacturing processes such as laser-directed energy deposition and selective laser melting. It effectively addresses the problems of low mechanical properties, insufficient corrosion resistance, easy precipitation of brittle phases in high-entropy alloy composites, or the use of high-entropy alloys only as alloying elements in existing additive titanium alloys. This provides a feasible approach for the preparation of high-strength, corrosion-resistant titanium-based composite additive components.

Description

Technical Field

[0001] This invention relates to the field of metal laser additive manufacturing technology, and in particular to a method for in-situ generation of Ti-containing high-entropy alloys using laser-based degraded melting additive manufacturing. Background Technology

[0002] Titanium alloys possess both high specific strength and excellent corrosion resistance, making them a core structural material in aerospace, marine engineering, and other fields. Laser additive manufacturing technology, with its near-net-shape forming and flexibility advantages, is widely used in the fabrication of complex titanium alloy components.

[0003] However, traditional additive titanium alloys have a coarse columnar crystal structure, and their mechanical properties, pitting corrosion resistance, and crevice corrosion resistance are insufficient to meet the high-end service requirements in chloride-containing environments. Adding high-entropy alloy powder can optimize corrosion resistance with elements such as Cr and Ni, but during conventional laser additive manufacturing, Ti easily reacts with Fe, Co, and Ni in the high-entropy alloy to form continuous brittle Ti-containing intermetallic compounds, disrupting the continuity of the passivation film. Simultaneously, the residual stress accumulated during rapid solidification easily induces defects such as micropores and microcracks, reducing mechanical properties and corrosion resistance. While conventional annealing can eliminate residual stress and defects to some extent, it cannot eliminate the Ti-containing intermetallic compounds generated during laser additive manufacturing due to high heat input, and this process is a post-processing step with a long workflow. Currently, there is a lack of methods for in-situ synergistic control of high-entropy alloy phases and metallurgical defects during additive manufacturing using low heat input, which restricts the engineering application of high-performance titanium-based composite materials. Summary of the Invention

[0004] In order to overcome the above-mentioned problems in the prior art, the present invention proposes a method for in-situ generation of Ti-containing high-entropy alloys by laser-based down-melting additive manufacturing.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for in-situ generation of Ti-containing high-entropy alloys by laser-based down-melting additive manufacturing, comprising the following steps: Step 1, substrate cleaning: Use industrial anhydrous ethanol to clean the surface of the titanium alloy substrate to remove oil and impurities. Step 2: Prepare deposited powder, which includes titanium alloy powder and high-entropy alloy powder. Titanium alloy composite powder with different contents of high-entropy alloy is prepared by planetary ball mill and dried at 120 °C for two hours. Step 3, laser-degraded melting additive manufacturing: The mixed powder is placed in the laser additive powder feeding system, and the composite material is obtained by layer-by-layer melting and deposition using a low heat input laser. After each layer is deposited, the forming process is paused, and the formed layer is scanned with a laser with progressively decreasing heat input 2 to 4 times. The deposition and multi-stage heat input reduction laser degraded scanning process are alternated and cycled until the overall component is formed. The composite material has fine equiaxed grains. The added high-entropy alloy powder reacts in situ with Ti in the titanium alloy matrix during the laser degradation melting additive manufacturing process to generate a new Ti-containing high-entropy alloy phase, which is dispersed in the composite material.

[0006] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser-induced degradation melting additive manufacturing has a grain size of 20 μm-120 μm.

[0007] In the above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser-induced degradation melting additive manufacturing, the mass fraction of the high-entropy alloy powder in step 2 is 0.5 wt.%~25 wt.%.

[0008] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser-induced degradation melting additive manufacturing, wherein the high-entropy alloy powder in step 2 is selected from at least one of the high-entropy alloys such as CoCrFeNi, AlCoCrFeNi, CoCrFeNiMn, CoCrFeNiW, CoCrFeNiMo, AlCrFeNiTi, TiAlVFeCr, and AlCrFeMnNi.

[0009] In the above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser-induced degradation melting additive manufacturing, the titanium alloy powder in step 2 can be α-type titanium alloy powder, near-α-type titanium alloy powder, β-type titanium alloy powder, or α+β-type titanium alloy powder.

[0010] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser degradation melting additive manufacturing includes a laser additive manufacturing process that is a type of laser directional energy deposition and selective laser melting.

[0011] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser degradation melting additive manufacturing, wherein the laser additive manufacturing is laser directional energy deposition, and the particle size of both the high-entropy alloy powder and the titanium alloy powder is 53μm-105μm.

[0012] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser degradation melting additive manufacturing, wherein the laser additive manufacturing is selective laser melting, and the particle size of both the high-entropy alloy powder and the titanium alloy powder is 15μm-45μm.

[0013] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser-degraded melting additive manufacturing, wherein the laser additive manufacturing is laser-directed energy deposition, and the deposition forming process parameters are: laser power of 1500 W~2500 W, scanning speed of 300 mm / min~2000 mm / min, and powder feeding rate of 3 g / min~15 g / min; the laser multi-stage degraded scanning is performed 2~4 times, the power of the first laser degraded scanning is 20%~70% of the deposition laser power, the power of each subsequent laser degraded scanning is reduced by 30%~60% compared with the previous one, the scanning speed is 1.0~2.0 times the forming scanning speed, and 2~4 multi-stage laser degraded scanning are performed for each formed layer.

[0014] The above-mentioned method for in-situ generation of Ti-containing high-entropy alloys by laser-based downgrade melting additive manufacturing, wherein the laser additive manufacturing is selective laser melting, and the forming process parameters are: laser power 80 W~300 W, scanning speed 400 mm / s~2500 mm / s, powder layer thickness 20 μm~80 μm; the laser multi-stage downgrade scanning is performed 1~4 times, the power of the first laser downgrade scan is 20%~70% of the forming laser power, the power of each subsequent laser downgrade scan is reduced by 30%~60% compared with the previous scan, the scanning speed is 1.0~2.0 times the forming scanning speed, and 2~4 multi-stage laser downgrade scans are performed for each formed layer.

[0015] The beneficial effects of this invention are that it uses a low-heat-input laser-degraded melting additive manufacturing integrated process to prepare high-strength and corrosion-resistant titanium-based composite materials. This breakthrough overcomes the bottlenecks of existing high-entropy alloy modified titanium alloy additive manufacturing systems, such as easy precipitation of brittle phases or high-entropy alloying elements only serving as alloying elements, large residual stress, and limited improvement in corrosion resistance. This invention can generate Ti-containing high-entropy alloys in situ during the forming process, and perform microstructure control and performance optimization without the need for additional subsequent heat treatment processes, effectively achieving a synergistic improvement in the corrosion resistance and mechanical properties of titanium alloys.

[0016] This method combines low-heat-input additive forming with multi-stage, heat-reducing interlayer laser scanning to significantly reduce peak heat input and precisely control the interdiffusion of interfacial elements. This avoids excessive reactions between Ti and Fe, Co, and Ni in the added high-entropy alloy caused by high-heat-input laser additive forming, inhibits the formation of continuous Ti-based brittle intermetallic compounds, and ensures the continuity and integrity of the substrate passivation film. Furthermore, the progressive temperature field during multi-pass laser downgrading scanning fully promotes moderate bidirectional interdiffusion between Ti and high-entropy alloy elements, improving the density and self-healing ability of the passivation film while producing solid solution strengthening. Ti elements in the titanium matrix diffuse into the high-entropy alloy phase, generating a novel Ti-containing high-entropy alloy phase in situ, further strengthening the phase interface and matrix structure. Simultaneously, multi-stage, heat-reducing interlayer laser scanning can eliminate residual stress accumulated during the forming process layer by layer and pass by pass, bridging micropores and interlayer micro-defects, blocking the propagation channels of corrosive media, and significantly inhibiting the initiation and propagation of microcracks. Under optimized process conditions, the self-corrosion current density of the composite material is reduced by more than an order of magnitude compared with that of pure additive titanium alloy, and the pitting potential is significantly improved. At the same time, the mechanical strength of the material is improved through multiple mechanisms such as fine grain strengthening, solid solution strengthening and second phase strengthening, thus achieving dual optimization of corrosion resistance and mechanical properties.

[0017] This invention is compatible with various laser additive manufacturing processes such as laser directional energy deposition and laser powder bed melting. The process flow is simple and highly controllable, providing a feasible solution for the low-cost and high-efficiency preparation of high-performance corrosion-resistant titanium alloy additive components. It has important engineering application value in harsh service fields such as marine engineering and aerospace. Attached Figure Description

[0018] Figure 1 These are comparative microstructures of laser-directed energy deposition (LDED) TC4-based composite materials prepared using different processes. (a) shows the microstructure of pure LDED TC4 titanium alloy; (b) shows the microstructure of LDED TC4 titanium alloy with added Al. 0.5 Microstructure of CoCrFeNi high-entropy alloy and TC4-based composite material without interlayer laser degradation scanning; (c) Microstructure of Al-added composite material. 0.5 Microstructure of TC4-based composite material with CoCrFeNi high-entropy alloy powder coupled with single-segment interlayer laser degradation scanning; (d) shows the microstructure of Al-added composite material. 0.5 Microstructure of TC4-based composite material containing CoCrFeNi high-entropy alloy powder coupled with multiple laser degradation scans.

[0019] Figure 2 The figures show a comparison of the comprehensive performance of laser-directed energy deposition samples prepared by different laser processes. (a) shows the potentiodynamic polarization curves of the samples in 3.5 wt.% NaCl solution; (b) shows a comparison of the tensile properties of the samples.

[0020] Figure 3The figures show a comparison of the comprehensive performance of selective laser melting samples prepared by different laser processes. (a) shows the potentiodynamic polarization curves of the samples in 3.5 wt.% NaCl solution; (b) shows a comparison of the tensile properties of the samples. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] This embodiment discloses a method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing, comprising the following steps: Step 1, substrate cleaning: Use industrial anhydrous ethanol to clean the surface of the titanium alloy substrate to remove oil and impurities. Step 2: Prepare deposited powder, which includes titanium alloy powder and high-entropy alloy powder. Titanium alloy composite powder with different contents of high-entropy alloy is prepared by planetary ball mill and dried at 120 °C for two hours. Step 3: Laser-degraded melting additive manufacturing. The mixed powder is placed in the laser additive powder feeding system, and the composite material is obtained by layer-by-layer melting and deposition using a low-heat-input laser. After each layer is deposited, the forming process is paused, and the formed layer is scanned with a laser with progressively decreasing heat input 2 to 4 times. During the scanning process, the deposited layer does not remelt. After the scanning is completed, the next layer is deposited. The deposition and multi-stage laser degraded scanning are alternated and cycled for 15 layers, and the forming height reaches 8 mm.

[0023] Compared to conventional additive manufacturing, the forming heat input of this invention is significantly reduced. Taking laser-directed energy deposition (LDED) as an example, the laser power in conventional TC4 additive manufacturing is typically 2500 W to 4000 W, with a high line energy density; the forming laser power of this invention is reduced to 1500 W to 2500 W, and the single-pass line energy density is reduced by approximately 20% to 30%. This reduces the high-temperature dwell time and peak temperature of the molten pool from the source, suppressing the excessive formation of brittle Ti-containing intermetallic compounds due to the excessive reaction between Ti and high-entropy alloying elements. Furthermore, after each layer is deposited, multiple laser scans with progressively decreasing heat input are performed, further achieving microstructure control and stress relief through a gradient temperature field, rather than relying on increasing the deposition heat input.

[0024] The composite material prepared by the above method uses a titanium alloy as the matrix, in which an in-situ generated Ti-containing high-entropy alloy phase is dispersed. The matrix structure is an α+β dual-phase structure or a matrix phase of the corresponding titanium alloy type, with uniform, fine, equiaxed grains ranging from 20 μm to 120 μm in size. The volume fraction of the Ti-based brittle intermetallic phase does not exceed 5%. Compared to additively manufactured titanium alloys without high-entropy alloys and conventionally manufactured titanium alloys with high-entropy alloys, the titanium alloy reinforced with in-situ generated Ti-containing high-entropy alloys by laser downsizing melting additive manufacturing exhibits superior mechanical properties and resistance to pitting and uniform corrosion.

[0025] In this embodiment, the mass fraction of the high-entropy alloy powder in step 2 is 0.5 wt.%~25 wt.%.

[0026] In this embodiment, the high-entropy alloy powder in step 2 is selected from at least one of the high-entropy alloys such as CoCrFeNi, AlCoCrFeNi, CoCrFeNiMn, CoCrFeNiW, CoCrFeNiMo, AlCrFeNiTi, TiAlVFeCr, and AlCrFeMnNi.

[0027] In this embodiment, the titanium alloy powder in step 2 can be α-type titanium alloy powder, near-α-type titanium alloy powder, β-type titanium alloy powder, or α+β-type titanium alloy powder.

[0028] Example 1 Based on the above method, step 3, the laser additive manufacturing process, is laser directional energy deposition. The forming process is as follows: laser power is 1500 W~2500 W, scanning speed is 300 mm / min~2000 mm / min, and powder feeding rate is 3 g / min~15 g / min. The laser multi-stage degradation scan is performed 2~4 times. The power of the first laser degradation scan is 20%~70% of the deposition laser power, and the power of each subsequent laser degradation scan is reduced by 30%~60% compared with the previous scan. The scanning speed is 1.0~2.0 times the forming scanning speed. 2~4 multi-stage laser degradation scans are performed for each formed layer.

[0029] In this embodiment, the forming laser power was 2100 W, the scanning speed was 1000 mm / min, the powder feeding rate was 8 g / min, and the overlap rate was 35%. The laser multi-stage power reduction interlayer scanning was performed in three stages: the first stage power was 700 W, the second stage power was 400 W, and the third stage power was 100 W, with the power decreasing step by step. The scanning speed was 1.0 to 2.0 times that of the forming scanning speed, and the scanning path and the deposition path were arranged at a 90° intersection. The experimental substrate was a pure Ti board.

[0030] Example 2 Based on the above method, step 3 of the laser additive manufacturing process is selective laser melting, and the forming process parameters are: laser power 80 W~300 W, scanning speed 400 mm / s~2500 mm / s, powder layer thickness 20 μm~80 μm; the laser multi-stage degradation scanning is performed 2~4 times, the power of the first laser degradation scan is 20%~70% of the forming laser power, and the power of each subsequent laser degradation scan is reduced by 30%~60% compared with the previous scan, the scanning speed is 1.0~2.0 times the forming scanning speed, and 2~4 multi-stage laser degradation scans are performed for each formed layer.

[0031] In this embodiment, the forming laser power is 200 W, the scanning speed is 800 mm / s, the powder layer thickness is 30 μm, and the scanning interval is 80 μm. The laser multi-stage power reduction interlayer scanning is performed in two steps, with the first pass power being 80 W and the second pass power being 30 W, and the power decreasing step by step. The annealing scanning speed is 1.0 to 2.0 times the forming scanning speed.

[0032] Based on the above method, TC4-Al was prepared. 0.5 The CoCrFeNi composite material underwent three laser scans with progressively decreasing heat input after each layer was formed, followed by the deposition of the next layer. This cycle was repeated for 15 layers, achieving a forming height of 8 mm. This process enabled in-situ control of the corrosion resistance and mechanical properties of laser-added TC4 titanium alloy. The specific steps are as follows: S1. Explore suitable laser-based degradation annealing additive manufacturing parameters and prepare corrosion-resistant TC4-based composite materials using an integrated low-heat-input laser deposition-multiple degradation laser scanning process.

[0033] In step S1, Al is selected 0.5 CoCrFeNi high-entropy alloy powder and TC4 titanium alloy powder were used to prepare Al content-containing alloys of different contents using a planetary ball mill. 0.5 CoCrFeNi TC4 composite powder was prepared and dried at 120 ℃ for 2 h. The mass percentage of each element in the TC4 titanium alloy powder was Ti≥90%, Al: 5.4%-6.2%, V: 3.8%-4.5%; Al 0.5 The mass percentages of each element in the CoCrFeNi high-entropy alloy powder are: Al: 4.8%-5.9%, Co: 23.0%-25.5%, Cr: 20.5%-22.6%, Fe: 22.3%-24.5%, and Ni: 23.8%-25.0%.

[0034] In step S1, the laser additive manufacturing process parameters include laser power, scanning speed, powder feeding rate, etc.; the interlayer multi-stage power reduction laser scanning process parameters include scanning passes, first pass power, power reduction ratio, scanning speed, etc.

[0035] Laser directed energy deposition process parameters range: laser power 1500 W~2500 W (conventional DED process is 2500 W~4000 W, the forming power of this invention is reduced by about 20%~30%), scanning speed 500 mm / min~1500 mm / min, powder feeding rate 5 g / min~12 g / min; Selective laser melting process parameter range: laser power 80 W~300 W (conventional SLM process is 200 W~400 W, the forming power of this invention is reduced by about 20%~30%), scanning speed 600 mm / s~1500 mm / s, powder layer thickness 20 μm~60 μm; The laser downgrading scan is performed 2 to 4 times. The power of the first laser scan is 20% to 70% of the forming laser power. The power of each subsequent annealing scan is reduced by 30% to 60% compared to the previous scan. The scanning speed is 1.0 to 2.0 times that of the forming scan speed. One round of multi-pass laser downgrading scan is performed for each formed layer.

[0036] TC4-Al was prepared using laser-degraded melting additive manufacturing technology. 0.5 CoCrFeNi corrosion-resistant titanium-based composite material: This preparation method avoids the limitations of traditional long and costly subsequent heat treatment processes. At the same time, it breaks through the bottleneck of excessive peak heat input in single-pass melting and forming, which easily aggravates the precipitation of brittle phases. It can complete the microstructure regulation and performance optimization in situ during the forming process, and achieve synergistic improvement of corrosion resistance and mechanical properties. It can be used as a general technical solution for additive manufacturing of high-performance corrosion-resistant titanium-based composite materials.

[0037] Composite materials were prepared based on the above method. Figure 1 The study showcases pure TC4 samples prepared by laser-directed energy deposition and TC4-3.0 wt.% Al without interlayer laser degradation scanning. 0.5 CoCrFeNi high-entropy alloy composite material, TC4-3.0 wt.% Al obtained by single-segment interlayer laser degradation scanning 0.5 CoCrFeNi high-entropy alloy composite material, TC4-3.0 wt.% Al obtained by multiple interlayer laser degradation scanning 0.5Microstructure comparison of CoCrFeNi high-entropy alloy composites. It can be seen that the pure TC4 additive sample exhibits a coarse columnar crystal structure with a grain size of approximately 400 μm to 600 μm, and micro-defects induced by residual stress exist at the grain boundaries. The sample with only high-entropy alloy added shows some grain refinement, with a grain size of approximately 100 μm to 200 μm, but brittle phase precipitation exists at the grain boundaries. The sample coupled with a single laser downgrade scan shows further grain refinement, with a grain size of approximately 80 μm to 120 μm, and a reduction in brittle phase precipitation, but the microstructure uniformity still needs improvement. The sample after adding high-entropy alloy coupled with multiple laser downgrade scans shows that the grains transform from coarse columnar crystals to uniform and fine equiaxed crystals, with a grain size of approximately 20 μm to 70 μm, no continuous brittle phase distribution at the grain boundaries, and a significantly improved microstructure density.

[0038] Figure 2 The potentiodynamic polarization curves and room-temperature mechanical properties of three groups of samples in 3.5 wt.% NaCl solution were compared. Experimental results show that the self-corrosion current density of the pure TC4 laser-directed energy deposition sample is 2.0 × 10⁻⁶. -7 A / cm 2 The yield strength is 711 MPa and the tensile strength is 991 MPa; only 3.0 wt.% Al was added. 0.5 After high-entropy alloying with CoCrFeNi, the self-corrosion current density of the sample decreased to 1.0 × 10⁻⁶. -7 A / cm 2 After a single-pass interlayer laser degradation scan, the self-corrosion current density of the sample decreased to 8.0 × 10⁻⁶. -8 A / cm 2 The yield strength was 1196 MPa and the tensile strength was 1302 MPa. After multiple interlayer laser degradation scans coupled with high-entropy alloy addition, the self-corrosion current density of the sample was further reduced to 6.3 × 10⁻⁶ MPa. -8 A / cm 2 Compared to pure TC4, it is about an order of magnitude lower, while the yield strength reaches 1472 MPa and the tensile strength reaches 1562 MPa, achieving a synergistic improvement in corrosion resistance and mechanical properties compared to pure TC4.

[0039] Figure 3 The potentiodynamic polarization curves and room-temperature mechanical properties of three groups of samples selectively laser-melted in 3.5 wt.% NaCl solution were compared. Experimental results show that the self-corrosion current density of the pure TC4 selectively laser-melted sample is 2.5 × 10⁻⁶. -7 A / cm 2 The yield strength is 825 MPa and the tensile strength is 1058 MPa; only 3.0 wt.% Al was added. 0.5After CoCrFeNi high-entropy alloying, the self-corrosion current density of the sample decreased to 2.0 × 10⁻⁶. -7 A / cm 2 After a single-pass interlayer laser degradation scan, the self-corrosion current density of the sample decreased to 1.0 × 10⁻⁶. -7 A / cm 2 The yield strength was 1185 MPa, and the tensile strength was 1278 MPa. After multiple interlayer laser degradation scans coupled with a high-entropy alloy, the self-corrosion current density of the sample was further reduced to 4.0 × 10⁻⁶ MPa. -8 A / cm 2 Compared to pure TC4, it is about an order of magnitude lower, while the yield strength reaches 1415 MPa and the tensile strength reaches 1508 MPa, achieving a synergistic improvement in corrosion resistance and mechanical properties.

[0040] The microstructure and corrosion resistance of laser-added titanium alloys were controlled by high-entropy alloying coupled with laser degradation melting. Cr and Ni, as passivation stabilizing elements, diffused fully into the titanium matrix through multi-stage laser degradation scanning, enhancing the compactness and self-healing ability of the passivation film. Al, Co, and Fe controlled the relative contents of the α and β phases, and, combined with dynamic recovery and recrystallization induced by progressive laser scanning, achieved the transformation from coarse columnar crystals to fine equiaxed crystals. Low-heat-input deposition combined with reduced-power laser scanning reduced the peak heat input by more than 35%, suppressing excessive interdiffusion and reaction between Ti and Fe, Co, and Ni, and preventing the formation of continuous Ti-based brittle intermetallic compounds at grain boundaries. Simultaneously, a multi-pass progressive temperature field promoted bidirectional interdiffusion between Ti and high-entropy alloying elements, strengthening the matrix through solid solution of alloying elements and generating a Ti-containing high-entropy alloy second phase in situ, further improving microstructure stability and mechanical properties. Laser degradation melting can also eliminate residual stress accumulated during the deposition process layer by layer and channel by channel, close defects such as micropores and microcracks, block the expansion channels of corrosive media, and simultaneously improve the corrosion resistance and mechanical properties of titanium alloys through multiple effects of fine grain strengthening, solid solution strengthening, second phase strengthening and interface structure optimization.

[0041] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its scope and spirit, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A method for in-situ generation of Ti-containing high-entropy alloys using laser-based degradative melting additive manufacturing, characterized in that, Includes the following steps: Step 1, substrate cleaning: Use industrial anhydrous ethanol to clean the surface of the titanium alloy substrate to remove oil and impurities. Step 2: Prepare deposited powder, which includes titanium alloy powder and high-entropy alloy powder. Titanium alloy composite powder with different contents of high-entropy alloy is prepared by planetary ball mill and dried at 120 °C for two hours. Step 3, laser-degraded melting additive manufacturing: The mixed powder is placed in the laser additive powder feeding system, and the composite material is obtained by layer-by-layer melting and deposition using a low heat input laser. After each layer is deposited, the forming process is paused, and the formed layer is scanned with a laser with progressively decreasing heat input 2 to 4 times. The deposition and multi-stage heat input reduction laser degraded scanning process are alternated and cycled until the overall component is formed. The composite material has fine equiaxed grains. The added high-entropy alloy powder reacts in situ with Ti in the titanium alloy matrix during the laser degradation melting additive manufacturing process to generate a new Ti-containing high-entropy alloy phase, which is dispersed in the composite material.

2. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 1, characterized in that, The grain size is 20 μm-120 μm.

3. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 1, characterized in that, In step 2, the mass fraction of the high-entropy alloy powder is 0.5 wt.% to 25 wt.%.

4. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 3, characterized in that... The high-entropy alloy powder in step 2 is selected from at least one of the following high-entropy alloys: CoCrFeNi, AlCoCrFeNi, CoCrFeNiMn, CoCrFeNiW, CoCrFeNiMo, AlCrFeNiTi, TiAlVFeCr, and AlCrFeMnNi.

5. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based degraded melting additive manufacturing according to claim 1, characterized in that, The titanium alloy powder in step 2 can be α-type titanium alloy powder, near-α-type titanium alloy powder, β-type titanium alloy powder, or α+β-type titanium alloy powder.

6. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 1, characterized in that, The laser additive manufacturing process is a type of laser directional energy deposition and selective laser melting process.

7. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 6, characterized in that, When the laser additive manufacturing is laser-directed energy deposition, the particle size of both the high-entropy alloy powder and the titanium alloy powder is 53μm-105μm.

8. The method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 6, characterized in that, When the laser additive manufacturing is selective laser melting, the particle size of both the high-entropy alloy powder and the titanium alloy powder is 15μm-45μm.

9. A method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 7, characterized in that, When the laser additive manufacturing is laser directional energy deposition, the forming process parameters are as follows: laser power is 1500W~2500W, scanning speed is 300 mm / min~2000 mm / min, and powder feeding rate is 3 g / min~15 g / min; the laser multi-stage degradation scan is performed 2~4 times, the power of the first laser degradation scan is 20%~70% of the deposition laser power, and the power of each subsequent laser degradation scan is reduced by 30%~60% compared with the previous scan. The scanning speed is 1.0~2.0 times the forming scanning speed, and 2~4 multi-stage laser degradation scans are performed for each layer formed.

10. A method for in-situ generation of Ti-containing high-entropy alloys using laser-based down-melting additive manufacturing according to claim 8, characterized in that, When the laser additive manufacturing is selective laser melting, the forming process parameters are: laser power 80 W~300 W, scanning speed 400 mm / s~2500 mm / s, and powder layer thickness 20 μm~80 μm; the laser multi-stage degradation scan is performed 2~4 times, the power of the first laser degradation scan is 20%~70% of the forming laser power, and the power of each subsequent laser degradation scan is reduced by 30%~60% compared with the previous scan, and the scanning speed is 1.0~2.0 times the forming scanning speed. 2~4 multi-stage laser degradation scans are performed for each formed layer.

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