Method for manufacturing high-entropy alloy from alloy raw material

Abstract

A method of forming a build weld from a high-entropy Ni-Cr-Nb-Mo-Ta alloy using a welding wire comprising a single core wire of pure nickel, pure chromium, pure niobium or pure molybdenum around which

Description

[0001] The present disclosure is related to the field of alloy manufacturing, and specifically to a method for manufacturing a high-entropy alloy from an alloy raw material. BACKGROUND

[0002] With the continuous development of materials science, high-entropy alloys, as a class of novel materials, have garnered significant attention due to their unique microstructures and exceptional properties. A high-entropy alloy is typically composed of five or more principal elements in an equiatomic ratio or a near-equiatomic ratio. This multi-component characteristic endows a high-entropy alloy with a high-entropy effect in thermodynamics, such that the high-entropy alloy demonstrates distinctly different physical, chemical, and mechanical properties from the conventional alloy.

[0003] As a member of the high-entropy alloy family, the refractory high-entropy alloy NiCrNbMoTa possesses characteristics such as high melting point, exceptional strength, excellent corrosion resistance, and prominent high-temperature stability. Thus, the refractory high-entropy alloy NiCrNbMoTa has a promising application prospect in extreme environments such as aerospace, nuclear energy, and chemical engineering. However, the traditional manufacturing methods for the refractory high-entropy alloy NiCrNbMoTa often face problems such as non-uniform components, complex manufacturing processes, and high costs, which limit the large-scale production and application of the refractory high-entropy alloy NiCrNbMoTa.

[0004] To overcome these challenges, researchers are continually exploring new manufacturing techniques and processes. The build-up welding using cable-type welding wires has emerged as a promising manufacturing method. In this method, high-melting-point metal wires or alloy wires are twisted into a cable-type welding wire, and the build-up welding is carried out by an advanced welding technique (such as tungsten inert gas (TIG)-based rotating wire arc additive welding manufacturing technology). This method can achieve the rapid, efficient, and low-cost production of the refractory high-entropy alloy NiCrNbMoTa.

[0005] As described in the patent document CN115302124B, the TIG-based rotating wire arc welding additive manufacturing technology is adopted to manufacture a high-entropy alloy with a cable-type welding wire. However, in the practical applications, there are still problems such as high energy consumption and need to improve hardness and strength. Due to these problems, the high-entropy alloy manufactured accordingly may exhibit unstable properties or cannot meet specific application requirements. Therefore, the further optimization of a composition design for a cable-type welding wire and build-up welding process parameters to enhance the quality and performance of the refractory high-entropy alloy NiCrNbMoTa holds significant research significance and application values. SUMMARY

[0006] Based on the above background, the present disclosure provides a novel method for manufacturing a refractory high-entropy alloy NiCrNbMoTa from an alloy raw material. By accurately designing a composition of a cable-type welding wire and optimizing build-up welding process parameters, the present disclosure achieves rapid, efficient, and low-cost production of a high-entropy alloy, and obtains a refractory high-entropy alloy product NiCrNbMoTa with excellent performance.

[0007] Specifically, a method for manufacturing a high-entropy alloy from an alloy raw material is provided, where the high-entropy alloy is a refractory high-entropy alloy NiCrNbMoTa, and the method includes the following steps:

[0008] step 1, twisting high-melting-point metal wires or alloy wires including a high-melting-point metal to produce a cable-type welding wire for the refractory high-entropy alloy, where the high-melting-point metal is one selected from a group consisting of Ni, Cr, Nb, Mo, and Ta; in the cable-type welding wire for the refractory high-entropy alloy, a core wire is a pure metal wire, and surrounding wires are bimetallic alloy wires; a total number of the core wire is one, and a total number of the surrounding wires is an integral multiple of 4; the core wire is one selected from a group consisting of a pure nickel wire, a pure chromium wire, a pure niobium wire, and a pure molybdenum wire; and the surrounding wires are the bimetallic alloy wires each including a metal element of the core wire and one of other four high-melting-point metal elements of Ni, Cr, Nb, Mo, and Ta, respectively, and numbers of the surrounding wires including the other four high-melting-point metal elements respectively are equal; and

[0009] step 2, conducting build-up welding with the cable-type welding wire for the refractory high-entropy alloy obtained in the step 1 to produce the refractory high-entropy alloy NiCrNbMoTa.

[0010] Preferably, a molar percentage of a same metal element in the surrounding wires as in the core wire is not less than 3% in the surrounding wires.

[0011] Preferably, the molar percentage of the same metal element in the surrounding wires as in the core wire is not more than 7% in the surrounding wires.

[0012] Preferably, the core wire has a diameter of 0.1 mm to 0.2 mm, and the surrounding wires each have a diameter of 0.5 mm to 0.75 mm.

[0013] Preferably, in the step 1, the total number of the surrounding wires is 4 or 8.

[0014] Preferably, the build-up welding is conducted by a TIG-based rotating wire arc welding additive manufacturing technology.

[0015] Preferably, the cable-type welding wire for the refractory high-entropy alloy is deposited on a substrate by the TIG-based rotating wire arc welding additive manufacturing technology to allow cladding and additive manufacturing.

[0016] Preferably, the step 2 further includes: placing the cable-type welding wire for the refractory high-entropy alloy in a wire feeder, setting a wire feed angle, a wire feed rate, and an additive manufacturing rate, and introducing pure argon for protection.

[0017] Preferably, the wire feed angle is 17° to 25°; the wire feed rate is 5 mm / s to 10 mm / s; the additive manufacturing rate is 150 mm / min to 200 mm / min; a welding current is 85 Ato 110 A; and an arc rotation rate is 200 r / min to 250 r / min.

[0018] A refractory high-entropy alloy NiCrNbMoTa manufactured by the method described above is provided.

[0019] Advantages:

[0020] Compared with the prior art, the use of the cable-type welding wire facilitates the regulation of a content of each metal. By controlling a type of a metal in a core wire and a percentage content of a central element in a surrounding wire, the contents of different metal elements in the high-entropy alloy can be easily adjusted.

[0021] The hardness and the strength of the high-entropy alloy can be adjusted by adjusting a diameter of a surrounding wire, a wire feed angle during a TIG-based welding process, etc.

[0022] Moreover, this method enables the additive manufacturing with a relatively-low welding current. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Example 1: Specific steps for manufacturing a refractory high-entropy alloy NiCrNbMoTa from an alloy raw material were as follows:

[0024] Step 1 : Fabrication of a cable-type welding wire for a refractory high-entropy alloy

[0025] Material selection and dimensions:

[0026] Core wire selection: A pure nickel wire with a diameter of 0.2 mm was selected as a core wire.

[0027] Surrounding wire selection: Four types of bimetallic alloy wires were selected as surrounding wires, including a nickel-chromium alloy wire, a nickel-niobium alloy wire, a nickel-molybdenum alloy wire, and a nickel-tantalum alloy wire. One alloy wire of each type was adopted, and there were four surrounding wires in total. In each alloy wire, a molar percentage of nickel was 3%. Each alloy wire had a diameter of 0.6 mm.

[0028] Twisting process:

[0029] One core wire and four surrounding wires were twisted in a core-surrounding arrangement manner. It should be guaranteed that the core wire was arranged at a center position and the surrounding wires were evenly distributed around the core wire to form a cable structure. During the twisting, it was necessary to ensure that the wires were in close contact with each other without any looseness or misalignment.

[0030] Step 2: Build-up welding

[0031] Equipment preparation:

[0032] The TIG-based rotating wire arc welding additive manufacturing technology was adopted. A TIG welding machine, a wire feeder, an argon protection device, etc. were prepared.

[0033] Parameter setting:

[0034] The cable-type welding wire for the refractory high-entropy alloy was placed in the wire feeder. A wire feed angle was set to 25°, a wire feed rate was set to 10 mm / s, and an additive manufacturing rate was set to 200 mm / min. A welding current was set to 85 A and an arc rotation rate was set to 200 r / min. Pure argon was introduced for protection.

[0035] Build-up welding operation:

[0036] A substrate (such as a stainless-steel plate) was placed on a welding platform. The TIG welding machine was started, and the build-up welding was conducted according to the preset parameters.

[0037] The cable-type welding wire for the refractory high-entropy alloy was delivered by the wire feeder to a welding region, and an arc rotation was allowed to melt the cable-type welding wire and a surface of the substrate to produce a molten pool. With the continuous feeding of the cable-type welding wire and the additive manufacturing on the substrate, the refractory high-entropy alloy NiCrNbMoTa layer was gradually formed on the substrate.

[0038] Post-treatment:

[0039] After the build-up welding was completed, the welding region was cooled to eliminate the residual stress and improve the microstructure and performance.

[0040] The necessary polishing and cleaning were conducted to remove spatters and oxides generated during the welding process.

[0041] Example!:

[0042] This example was different from Example 1 merely in that, in the step 1, the molar percentage of nickel in each alloy wire was 5%.

[0043] Example3:

[0044] This example was different from Example 1 merely in that, in the step 1, the molar percentage of nickel in each alloy wire was 7%.

[0045] Comparative Example 1:

[0046] This comparative example was different from Example 1 merely in that, in the step 1, the molar percentage of nickel in each alloy wire was 2%.

[0047] Comparative Example 2:

[0048] This comparative example was different from Example 1 merely in that, in the step 1, the molar percentage of nickel in each alloy wire was 8%.

[0049] Example 4:

[0050] This example was different from Example 2 merely in that, in the step 1, the core wire was made of chromium, the four surrounding wires were each made of an alloy including chromium and one of four other elements, respectively, and the molar percentage of chromium in each alloy wire was 5%.

[0051] Example5:

[0052] This example was different from Example 2 merely in that, in the step 1, the core wire was made of niobium, the four surrounding wires were each made of an alloy including niobium and one of four other elements, respectively, and the molar percentage of niobium in each alloy wire was 5%.

[0053] Example 6:

[0054] This example was different from Example 2 merely in that, in the step 1, the core wire was made of molybdenum, the four surrounding wires were each made of an alloy including molybdenum and one of four other elements, respectively, and the molar percentage of molybdenum in each alloy wire was 5%.

[0055] Comparative Example 3:

[0056] This comparative example was different from Example 2 merely in that, in the step 1, the core wire was made of tantalum, the four surrounding wires were each made of an alloy including tantalum and one of four other elements, respectively, and the molar percentage of tantalum in each alloy wire was 5%.

[0057] Example 7:

[0058] This example was different from Example 5 merely in that, in the step 1, the molar percentage of niobium in each alloy wire was 6%.

[0059] Examples:

[0060] This example was different from Example 5 merely in that, in the step 1, the molar percentage of niobium in each alloy wire was 7%.

[0061] Example 9:

[0062] This example was different from Example 5 merely in that, in the step 1, each alloy wire had a diameter of 0.5 mm.

[0063] Example 10:

[0064] This example was different from Example 5 merely in that, in the step 1, each alloy wire had a diameter of 0.75 mm.

[0065] Comparative Example 4:

[0066] This comparative example was different from Example 5 merely in that, in the step 1, each alloy wire had a diameter of 0.9 mm.

[0067] Example 11:

[0068] This example was different from Example 5 merely in that, in the step 2, the wire feed angle was 20°.

[0069] Example 12:

[0070] This example was different from Example 5 merely in that, in the step 2, the wire feed angle was 17°.

[0071] Comparative Example 5:

[0072] This comparative example was different from Example 5 merely in that, in the step 2, the wire feed angle was 14°.

[0073] Comparative Example 6:

[0074] This comparative example was different from Example 5 merely in that, in the step 2, the wire feed angle was 28°.

[0075] The high-entropy alloys obtained in the above examples and comparative examples were each characterized for a micro Vickers hardness, a yield strength, and thermal stability.

[0076] ____________________________________________________________________________________ Vickers hardness (HV) Yield strength (MPa) Fracture strain (%) Example 1 1059 734 7.6 Example 2 1186 857 8.8 Example 3 1240 918 10.5 Comparative Example 1 1104 531 4.2 Comparative Example 2 849 779 9.7 Example 4 1223 929 9.3 Example 5 1312 1097 11.0 Example 6 1336 1115 11.4 Comparative Example 3 1340 1229 5.7 Example 7 1398 1257 11.8 Example 8 1457 1329 12.4 Example 9 1289 1084 10.7 Example 10 1325 1124 11.3 Comparative Example 4 1413 903 7.9 Example 11 1344 1089 11.0 Example 12 1377 1091 10.9 Comparative Example 5 905 1067 10.4 Comparative Example 6 1320 824 6.3

[0077] In the present application, a content of a central element in the surrounding alloy wire has a significant impact on the Vickers hardness and the yield strength. Within a specified range, as the molar percentage of the central element increases (as in Examples 1 to 3, 5, and 7 to 8), both the hardness and the strength increase and remain at relatively-high levels. When the molar percentage of the central element is too low (as in Comparative Example 1), the hardness of the material can be maintained at a high level, but the yield strength and fracture strain are significantly reduced. When the molar percentage of the central element is too high (as in Comparative Example 2), the material still possesses a large fracture strain, but has a yield strength and Vickers hardness that are significantly reduced.

[0078] In the technical solution of the present application, the element of the core wire can be easily replaced, such that the molar percentages of different metal elements can be significantly adjusted. The different elements selected for the core wire lead to varying hardnesses, yield strengths, and fracture strains. According to characterization results, when a high-melting-point metal element is adopted as the core wire, the parameters such as a hardness, a yield strength, and a fracture strain of the alloy finally produced are improved to varying degrees. When tantalum is adopted as the element of the core wire (in Comparative Example 3), the hardness does not significantly change, but the fracture strain is remarkably reduced.

[0079] In the technical solution of the present application, the diameter of the surrounding alloy wire has a specified impact on the yield strength and fracture strain of the material. The diameter of the surrounding wire should be controlled within a specified range. When the diameter is too large (as in Comparative Example 4), the yield strength and fracture strain will significantly decrease.

[0080] In the technical solution of the present application, the wire feed angle during the additive manufacturing process is also a key parameter. The wire feed angle can be reduced within a specified range to enhance the strength of the material. However, when the wire feed angle is too small (as in Comparative Example 5), the hardness of the material drops sharply. When the wire feed angle is too large (as in Comparative Example 6), the yield strength and fracture strain of the material significantly decrease.

Claims

1. A method for manufacturing a high-entropy alloy from an alloy raw material, wherein the high-entropy alloy is a refractory high-entropy alloy NiCrNbMoTa, and the method comprises the following steps:step 1, twisting high-melting-point metal wires or alloy wires comprising a high-melting-point metal to produce a cable-type welding wire for the refractory high-entropy alloy, wherein the high-melting-point metal is one selected from a group consisting of Ni, Cr, Nb, Mo, and Ta; in the cable-type welding wire for the refractory high-entropy alloy, a core wire is a pure metal wire, and surrounding wires are bimetallic alloy wires; a total number of the core wire is one, and a total number of the surrounding wires is an integral multiple of 4; the core wire is one selected from a group consisting of a pure nickel wire, a pure chromium wire, a pure niobium wire, and a pure molybdenum wire; and the surrounding wires are the bimetallic alloy wires each comprising a metal element of the core wire and one of other four high-melting-point metal elements of Ni, Cr, Nb, Mo, and Ta, respectively, and numbers of the surrounding wires comprising the other four high-melting-point metal elements respectively are equal; andstep 2, conducting build-up welding with the cable-type welding wire for the refractory high-entropy alloy obtained in the step 1 to produce the refractory high-entropy alloy NiCrNbMoTa.

2. The method for manufacturing the high-entropy alloy from the alloy raw material according to claim 1, wherein a molar percentage of a same metal element in the surrounding wires as in the core wire is not less than 3% in the surrounding wires.

3. The method for manufacturing the high-entropy alloy from the alloy raw material according to claim 2, wherein the molar percentage of the same metal element in the surrounding wires as in the core wire is not more than 7% in the surrounding wires.

4. The method for manufacturing the high-entropy alloy from the alloy raw material according to claim 1, wherein the core wire has a diameter of 0.1 mm to 0.2 mm, and the surrounding wires each have a diameter of 0.5 mm to 0.75 mm.

5. The method for manufacturing the high-entropy alloy from the alloy raw materialaccording to claim 1, wherein in the step 1, the total number of the surrounding wires is 4 or 8.

6. The method for manufacturing the high-entropy alloy from the alloy raw materialaccording to claim 1, wherein the build-up welding is conducted by a tungsten inert gas(TIG)-based rotating wire arc welding additive manufacturing technology.

7. The method for manufacturing the high-entropy alloy from the alloy raw material according to claim 6, wherein the cable-type welding wire for the refractory high-entropy alloy is deposited on a substrate by the TIG-based rotating wire arc welding additive manufacturing technology to allow cladding and additive manufacturing.

8. The method for manufacturing the high-entropy alloy from the alloy raw material according to claim 7, wherein the step 2 further comprises: placing the cable-type welding wire for the refractory high-entropy alloy in a wire feeder, setting a wire feed angle, a wire feed rate, and an additive manufacturing rate, and introducing pure argon for protection.

9. The method for manufacturing the high-entropy alloy from the alloy raw material according to claim 8, wherein the wire feed angle is 17° to 25°; the wire feed rate is 5 mm / s to 10 mm / s; the additive manufacturing rate is 150 mm / min to 200 mm / min; a welding current is 85 A to 110 A; and an arc rotation rate is 200 r / min to 250 r / min.

10. A refractory high-entropy alloy NiCrNbMoTa manufactured by the method according to any one of claims 1 to 9.11