A method for preparing a high-toughness eutectic high-entropy alloy

Abstract

This invention provides a method for preparing high-strength and high-toughness eutectic high-entropy alloys, belonging to the field of metal material processing technology. In this invention, a eutectic high-entropy alloy is first prepared using hot pressing technology. Then, an indentation is created on the surface of the hot-pressed eutectic high-entropy alloy using a stamping bulging technique. Next, a eutectic high-entropy alloy coating is prepared on the surface of the hot-pressed eutectic alloy using laser cladding technology. The heat generated by laser cladding can be rapidly transferred to the heated eutectic high-entropy alloy substrate through the indentation, meeting the stringent requirements for the preparation of the eutectic high-entropy alloy microstructure. Eutectic high-entropy alloys of the same specifications are then prepared using the same method. One side of the coating is butt-jointed and stacked together, followed by hot rolling. Because one side of the coating has a cast microstructure, the two materials can be effectively bonded together. Therefore, the eutectic high-entropy alloy material prepared by this invention has excellent strength and toughness properties, and large-size eutectic high-entropy alloys can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology and relates to a method for preparing a high-strength and high-toughness eutectic high-entropy alloy. Background Technology

[0002] Eutectic high-entropy alloys, with their biphase (BCC+FCC) layered heterostructure, exhibit damping and giant magnetoresistance effects, making them highly promising for applications in defense, military, and aerospace fields. However, eutectic high-entropy alloys prepared by traditional methods suffer from poor mechanical properties, limiting their practical application in manufacturing.

[0003] The preparation of eutectic high-entropy alloys requires ensuring the formation of a stable eutectic structure, which places extremely stringent demands on the preparation technology. Currently, the most common technique for preparing eutectic alloys is the traditional casting method. While casting is a mature and simple process for preparing eutectic high-entropy alloys, it results in a coarse eutectic structure, significantly limiting the material's strength and toughness. Therefore, exploring a eutectic high-entropy alloy with both good strength and excellent plasticity, and its preparation method, has significant research importance and application value. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing high-strength and high-toughness eutectic high-entropy alloys. In this invention, the eutectic high-entropy alloy is first prepared using hot pressing technology. Since the hot pressing process mainly involves bonding between powders, the resulting billet has a lower height and less deformation, thus resulting in a lower texture content and reducing adverse effects on the mechanical properties of the eutectic high-entropy alloy material. However, if the height of the hot-pressed eutectic high-entropy alloy material is too high, it will lead to weaker bonding between powders and fracture during loading. Therefore, this technology further utilizes stamping bulging technology to create indentations on the surface of the hot-pressed eutectic high-entropy alloy, and then employs laser cladding technology to prepare a eutectic high-entropy alloy coating on the hot-pressed eutectic alloy surface. During laser cladding, the hot-pressed billet substrate is placed on a processing platform at 300–400°C, allowing the heat generated by laser cladding to be rapidly transferred to the heated eutectic high-entropy alloy substrate through the indentations. This ensures temperature and compositional uniformity between the substrate and the cladding material, avoiding temperature and compositional segregation that occurs during conventional laser cladding. This meets the stringent requirements for eutectic high-entropy alloy microstructure preparation, ensuring that the prepared coating remains a eutectic high-entropy alloy. Using the same method, eutectic high-entropy alloys of the same specifications are prepared by butt-jointing and stacking one side of the coating, followed by hot rolling with a reduction of 40%–60%. Since one side of the coating is in a cast state, the two materials can bond effectively, enabling the preparation of eutectic high-entropy alloy materials with different heights. Therefore, the eutectic high-entropy alloy material prepared by this invention has good strength and toughness properties, and can realize the preparation of large-size eutectic high-entropy alloys.

[0005] This invention first provides a method for preparing a high-strength and high-toughness eutectic high-entropy alloy. The eutectic high-entropy alloy has a uniform and fine grain structure, and the tensile strength of the eutectic high-entropy alloy material at room temperature is 1150-1250 MPa, and the elongation is 11.4%-14.6%.

[0006] Furthermore, the eutectic high-entropy alloy material is a FeCoNiCrAl-based eutectic high-entropy alloy.

[0007] This invention provides a method for preparing high-strength and high-toughness eutectic high-entropy alloys, specifically including the following steps:

[0008] (1) The vacuum-atomized eutectic high-entropy alloy powder and the mold are heated and kept at a certain temperature. Then, the eutectic high-entropy alloy powder is poured into the hot press mold, and the hot press sintering treatment is carried out by the press and the pressure is kept. Finally, the hot press blank is ejected by the ejection device. The heat preservation temperature and heat preservation time of the eutectic high-entropy alloy powder and the hot press mold are the same. The heat preservation temperature is 450-500℃ and the heat preservation time is 60-80min.

[0009] (2) Place the billet obtained in step (1) into a heat treatment furnace and perform low-temperature homogenization heat treatment. The heat treatment temperature is 200℃ and the holding time is 240min.

[0010] (3) Place the blank obtained in step (2) into the "well" shaped stamping bulging mold and prepare a "well" shaped indentation of a certain depth on the surface of the blank. The indentation depth is 0.1 mm.

[0011] (4) The billet obtained in step (3) is used as the base material and placed on a processing platform with a heating coil. The raw material is eutectic high entropy alloy powder. The eutectic high entropy alloy is prepared on the surface of the base material by laser cladding technology. The laser power is 1000-1200W, the spot diameter is 4-6mm, the scanning speed is 5-8mm / s, the overlap rate is 40-60%, and the powder feeding speed is 6-14g / min. A eutectic high entropy alloy coating is prepared on the surface of the hot-pressed eutectic high entropy alloy billet.

[0012] (5) Repeat steps (1) to (4) to prepare two eutectic high entropy alloys of the same specifications. Then, the coated side is butted and stacked together, and then hot rolled with a reduction of 40% to 60% to obtain a high-strength and high-toughness eutectic high entropy alloy.

[0013] Furthermore, in step (1), the size range of the eutectic high-entropy alloy powder is 15–53 μm.

[0014] Furthermore, in step (1), the length × width × height of the prepared hot-pressed blank is 100 × 100 × 40 mm.

[0015] Furthermore, in step (1), the pressure of hot pressing is 80-200 MPa.

[0016] Furthermore, in step (1), the cooling method after hot pressing is water cooling.

[0017] Furthermore, in step (2), the cooling method after heat treatment is water cooling.

[0018] Furthermore, in step (3), the spacing between the horizontal and vertical bars of the "well" shape is 1 mm.

[0019] Furthermore, in step (4), the temperature of the processing platform is 300-400℃.

[0020] Furthermore, in step (4), the size range of the eutectic high-entropy alloy powder is 15–53 μm.

[0021] Furthermore, in step (5), the hot rolling temperature is 640–680°C.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The high-strength and high-toughness eutectic high-entropy alloy material prepared by this invention has a uniform and fine grain structure. The tensile strength of the prepared eutectic high-entropy alloy material at room temperature is 1150-1250 MPa and the elongation is 11.4%-14.6%, which can be well used in actual working conditions.

[0024] The preparation of eutectic high-entropy alloys requires ensuring the formation of a stable eutectic structure, which places extremely stringent demands on the preparation technology. Traditional casting methods produce eutectic high-entropy alloys with coarse microstructures, significantly limiting the material's strength and toughness. This invention employs hot pressing technology to prepare eutectic high-entropy alloys. Since hot pressing primarily involves bonding between powder particles, the resulting billet has a lower height and less deformation, thus exhibiting a lower texture content. This reduces the adverse effects on the mechanical properties of the eutectic high-entropy alloy. However, excessively high height in the hot-pressed eutectic high-entropy alloy can lead to weaker bonding between powder particles and fracture under load. Therefore, this technology further utilizes stamping bulging technology to create indentations on the surface of the hot-pressed eutectic high-entropy alloy, and then employs laser cladding technology to prepare a eutectic high-entropy alloy coating on the hot-pressed eutectic alloy surface. During laser cladding, the hot-pressed billet serves as the substrate, placed on a processing platform at 300–400°C. The heat generated by laser cladding can be rapidly transferred to the heated eutectic high-entropy alloy substrate through the indentations, ensuring temperature and compositional uniformity between the substrate and the cladding material. This avoids the temperature and compositional segregation that occurs during conventional laser cladding, meeting the stringent requirements for eutectic high-entropy alloy microstructure preparation. Therefore, the prepared coating can still be guaranteed to be a eutectic high-entropy alloy. Using the same method, eutectic high-entropy alloys of the same specifications are prepared by butt-jointing and stacking one side of the coating together, followed by hot rolling with a reduction of 40%–60%. Since one side of the coating is in a cast state, the two materials can be effectively bonded, enabling the preparation of eutectic high-entropy alloy materials with different heights. Therefore, the eutectic high-entropy alloy material prepared by this invention has good strength and toughness properties, and can realize the preparation of large-size eutectic high-entropy alloys. Attached Figure Description

[0025] Figure 1 The image shows the microstructure of the eutectic high-entropy alloy material prepared in Example 1 of this invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0027] Example 1:

[0028] (1) The vacuum-atomized eutectic high-entropy alloy powder and the mold are heated and kept at a certain temperature. The size range of the high-entropy alloy powder is 15-53μm. Then, the eutectic high-entropy alloy powder is poured into the hot press mold and hot-pressed and sintered using a press and kept at a certain pressure. The hot pressing pressure is 180MPa, the holding temperature is 480℃, and the holding time is 70min. Finally, the hot-pressed blank is ejected using an ejection device. The length × width × height of the prepared hot-pressed blank is 100×100×40mm.

[0029] (2) Place the billet obtained in step (1) into a heat treatment furnace for low-temperature homogenization heat treatment. The heat treatment temperature is 200℃, the holding time is 240min, and the cooling method is water cooling.

[0030] (3) Place the blank obtained in step (2) into the "well" shaped stamping bulging mold and prepare a "well" shaped indentation of a certain depth on the surface of the blank. The spacing between the horizontal and vertical bars of the "well" is 1 mm and the indentation depth is 0.1 mm.

[0031] (4) The billet obtained in step (3) is used as the base material and placed on a processing platform with a heating coil. The temperature of the processing platform is 400℃. The raw material is eutectic high entropy alloy powder. The size range of the high entropy alloy powder is 15~53μm. The eutectic high entropy alloy is prepared on the surface of the base material by laser cladding technology. The laser power is 1000W, the spot diameter is 4mm, the scanning speed is 5mm / s, the overlap rate is 50%, and the powder feeding speed is 6g / min. A eutectic high entropy alloy coating is prepared on the surface of the hot-pressed eutectic high entropy alloy billet.

[0032] (5) Repeat steps (1) to (4) to prepare two eutectic high entropy alloys of the same specifications. Then, the coated side is butted and stacked together, and then hot-rolled. The hot rolling temperature is 640℃ and the reduction is 60% to obtain a high-strength and high-toughness eutectic high entropy alloy.

[0033] The microstructure of the prepared eutectic high-entropy alloy material was characterized, and its room-temperature tensile mechanical properties were tested to meet national standards. For example... Figure 1 The eutectic high-entropy alloy material exhibits a uniform and fine microstructure. It has a tensile strength of 1250 MPa and an elongation of 14.6%.

[0034] Example 2:

[0035] It is basically the same as Example 1, but with the following changes: the pressure of hot pressing in step (1) is 100 MPa.

[0036] The prepared eutectic high-entropy alloy material was subjected to room temperature tensile mechanical property tests that meet national standards. The tensile strength was 1150 MPa and the elongation was 11.4%.

[0037] Example 3:

[0038] It is basically the same as Example 1, but with the following changes: the hot rolling temperature in step (5) is 680°C.

[0039] The prepared eutectic high-entropy alloy material was subjected to room temperature tensile mechanical property tests that met national standards. The tensile strength was 1170 MPa and the elongation was 12.3%.

[0040] Example 4:

[0041] It is basically the same as Example 1, but with the following changes: the amount of pressure in step (5) is 50%.

[0042] The prepared eutectic high-entropy alloy material was subjected to room temperature tensile mechanical property tests that met national standards. The tensile strength was 1220 MPa and the elongation was 13.8%.

[0043] Comparative Example 1:

[0044] (1) The vacuum-atomized eutectic high-entropy alloy powder and the mold are heated and kept at a certain temperature. The size range of the high-entropy alloy powder is 15-53μm. Then, the eutectic high-entropy alloy powder is poured into the hot press mold and hot-pressed and sintered using a press and kept at a certain pressure. The hot pressing pressure is 180MPa, the holding temperature is 480℃, and the holding time is 70min. Finally, the hot-pressed blank is ejected using an ejection device. The length × width × height of the prepared hot-pressed blank is 100×100×40mm.

[0045] (2) Place the billet obtained in step (1) into a heat treatment furnace and perform low-temperature homogenization heat treatment. The heat treatment temperature is 200℃, the holding time is 240min, and the cooling method is water cooling to obtain the finished product.

[0046] The prepared eutectic high-entropy alloy material was subjected to room temperature tensile mechanical property tests that meet national standards. The tensile strength was 940 MPa and the elongation was 9.5%.

[0047] Comparative Example 2:

[0048] (1) The vacuum-atomized eutectic high-entropy alloy powder and the mold are heated and kept at a certain temperature. The size range of the high-entropy alloy powder is 15-53μm. Then, the eutectic high-entropy alloy powder is poured into the hot press mold and hot-pressed and sintered using a press and kept at a certain pressure. The hot pressing pressure is 180MPa, the holding temperature is 480℃, and the holding time is 70min. Finally, the hot-pressed blank is ejected using an ejection device. The length × width × height of the prepared hot-pressed blank is 100×100×40mm.

[0049] (2) Place the billet obtained in step (1) into a heat treatment furnace for low-temperature homogenization heat treatment. The heat treatment temperature is 200℃, the holding time is 240min, and the cooling method is water cooling.

[0050] (3) The billet obtained in step (2) is used as the base material and placed on a processing platform with a heating coil. The temperature of the processing platform is 400℃. The raw material is eutectic high entropy alloy powder. The size range of the high entropy alloy powder is 15~53μm. The eutectic high entropy alloy is prepared on the surface of the base material by laser cladding technology. The laser power is 1000W, the spot diameter is 4mm, the scanning speed is 5mm / s, the overlap rate is 50%, and the powder feeding speed is 6g / min. A eutectic high entropy alloy coating is prepared on the surface of the hot-pressed eutectic high entropy alloy billet.

[0051] (4) Repeat steps (1) to (3) to prepare two eutectic high entropy alloys of the same specifications. Then, the coated side is butted and stacked together, and then hot-rolled. The hot rolling temperature is 640℃ and the reduction is 60% to obtain the finished product.

[0052] The prepared eutectic high-entropy alloy material was subjected to room temperature tensile mechanical property tests that met national standards. The tensile strength was 1050 MPa and the elongation was 10.6%.

[0053] Comparative Example 3:

[0054] (1) The vacuum-atomized eutectic high-entropy alloy powder and the mold are heated and kept at a certain temperature. The size range of the high-entropy alloy powder is 15-53μm. Then, the eutectic high-entropy alloy powder is poured into the hot press mold and hot-pressed and sintered using a press and kept at a certain pressure. The hot pressing pressure is 180MPa, the holding temperature is 480℃, and the holding time is 70min. Finally, the hot-pressed blank is ejected using an ejection device. The length × width × height of the prepared hot-pressed blank is 100×100×40mm.

[0055] (2) Place the billet obtained in step (1) into a heat treatment furnace for low-temperature homogenization heat treatment. The heat treatment temperature is 200℃, the holding time is 240min, and the cooling method is water cooling.

[0056] (3) Place the blank obtained in step (2) into the "well" shaped stamping bulging mold and prepare a "well" shaped indentation of a certain depth on the surface of the blank. The spacing between the horizontal and vertical bars of the "well" is 1 mm and the indentation depth is 0.1 mm.

[0057] (4) The billet obtained in step (3) is used as the base material and placed on a processing platform with a heating coil. The temperature of the processing platform is 400℃. The raw material is eutectic high-entropy alloy powder with a size range of 15~53μm. The eutectic high-entropy alloy is prepared on the surface of the base material using laser cladding technology. The laser power is 1000W, the spot diameter is 4mm, the scanning speed is 5mm / s, the overlap rate is 50%, and the powder feeding speed is 6g / min. A eutectic high-entropy alloy coating is prepared on the surface of the hot-pressed eutectic high-entropy alloy billet to obtain the finished product.

[0058] The prepared eutectic high-entropy alloy material was subjected to room temperature tensile mechanical property tests that met national standards. The tensile strength was 980 MPa and the elongation was 11.6%.

[0059] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a high strength and toughness eutectic high-entropy alloy, characterized in that, Specifically, the steps include the following: (1) The vacuum-atomized eutectic high-entropy alloy powder and the mold are heated and kept at the same temperature. Then the eutectic high-entropy alloy powder is poured into the hot press mold, and the hot press sintering treatment is carried out by the press and the pressure is kept. Finally, the hot press blank is ejected by the ejection device. The heat preservation temperature and heat preservation time of the eutectic high-entropy alloy powder and the hot press mold are the same. The heat preservation temperature is 450~500℃ and the heat preservation time is 60~80min. (2) Place the billet obtained in step (1) into a heat treatment furnace for low-temperature homogenization heat treatment. The heat treatment temperature is 200℃ and the holding time is 240min. (3) Place the blank obtained in step (2) into the "well" shaped stamping bulging die and prepare a "well" shaped indentation of a certain depth on the surface of the blank. The indentation depth is 0.1 mm. (4) The billet obtained in step (3) is used as the base material and placed on a processing platform with a heating coil. The raw material is eutectic high entropy alloy powder. The eutectic high entropy alloy is prepared on the surface of the base material by laser cladding technology. The laser power is 1000-1200W, the spot diameter is 4-6mm, the scanning speed is 5-8mm / s, the overlap rate is 40-60%, and the powder feeding speed is 6-14g / min. A eutectic high entropy alloy coating is prepared on the surface of the hot-pressed eutectic high entropy alloy billet. (5) Repeat steps (1) to (4) to prepare two eutectic high entropy alloys of the same specifications. Then, the coated side is butted and stacked together, and then hot rolled with a reduction of 40% to 60% to obtain a high-strength and high-toughness eutectic high entropy alloy. The high-strength and high-toughness eutectic high-entropy alloy is a FeCoNiCrAl-based eutectic high-entropy alloy.

2. The method for preparing a high-strength and high-toughness eutectic high-entropy alloy according to claim 1, characterized in that, In step (1), the size range of the eutectic high-entropy alloy powder is 15~53μm.

3. The method for preparing a high-strength and high-toughness eutectic high-entropy alloy according to claim 1, characterized in that, In step (1), the length × width × height of the hot-pressed blank is 100 × 100 × 40 mm.

4. The method for preparing a high-strength and high-toughness eutectic high-entropy alloy according to claim 1, characterized in that, In step (1), the pressure of hot pressing is 80~200MPa.

5. The method of claim 1, wherein the high strength and toughness eutectic high-entropy alloy is prepared by the following steps of: In step (1), the cooling method after hot pressing is water cooling. ​ 6. The method of claim 1, wherein the high strength and toughness eutectic high-entropy alloy is prepared by the following steps of: In step (2), the cooling method after heat treatment is water cooling. ​ 7. The method for preparing a high-strength and high-toughness eutectic high-entropy alloy according to claim 1, characterized in that, In step (3), the spacing between the horizontal and vertical bars of the "well" shape is 1 mm.

8. The method for preparing a high-strength and high-toughness eutectic high-entropy alloy according to claim 1, characterized in that, In step (4), the temperature of the processing platform is 300~400℃.

9. The method for preparing a high-strength and high-toughness eutectic high-entropy alloy according to claim 1, characterized in that, In step (4), the size range of the eutectic high-entropy alloy powder is 15~53μm.

10. The method of claim 1, wherein the high strength and toughness eutectic high-entropy alloy is prepared by the following steps of: In step (5), the hot rolling temperature is 640~680℃. ​ 11. A high-strength, high-toughness eutectic high-entropy alloy prepared according to any one of claims 1 to 10, characterized in that, The eutectic high-entropy alloy has a tensile strength of 1150~1250MPa and an elongation of 11.4%~14.6% at room temperature.

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