Method for preparing high-entropy alloy from alloy raw materials

Abstract

According to the novel method for preparing the NiCrNbMoTa refractory high-entropy alloy from the alloy raw materials, the performance and the like of the high-entropy alloy can be controlled by regulating and controlling parameters such as the welding wire structure, the element proportion, the peripheral wire diameter and the TIG welding index, and a high-entropy alloy product with excellent and stable performance is obtained.

Description

Background Art

[0001] With the continuous development of materials science, high entropy alloys, as a new type of material, have attracted much attention due to their unique microstructure and excellent performance. High entropy alloys are usually composed of five or more main elements mixed in an equiatomic ratio or a near-equiatomic ratio. This multi-component characteristic makes high entropy alloys have a high entropy effect in thermodynamics, thus showing physical, chemical and mechanical properties that are completely different from traditional alloys.

[0002] As a member of the high entropy alloy family, NiCrNbMoTa refractory high entropy alloy has broad application prospects in extreme environments such as aerospace, nuclear energy, and chemical industry due to its high melting point, high strength, good corrosion resistance, and high temperature stability. However, traditional preparation methods often have problems such as uneven composition, complex preparation process, and high cost, which limit the large-scale production and application of NiCrNbMoTa refractory high entropy alloy.

[0003] In order to overcome these difficulties, researchers are constantly exploring new preparation technologies and methods. Among them, the use of cable welding wire for surfacing treatment is a potential preparation method. This method twists high-melting-point metal wires or alloy wires into cable welding wires and uses advanced welding technology (such as TIG rotating wire arc welding additive technology) for surfacing treatment, which can achieve fast, efficient and low-cost preparation of NiCrNbMoTa refractory high-entropy alloys.

[0004] For example, in patent document CN115302124B, TIG rotating wire arc welding additive technology is used to prepare high entropy alloys using cable welding wires. However, in actual applications, there are still problems such as high energy consumption and the need to improve hardness and strength. These problems may cause the prepared high entropy alloys to have unstable performance or fail to meet specific application requirements. Therefore, further optimizing the composition design and surfacing process parameters of cable welding wires to improve the preparation quality and performance of NiCrNbMoTa refractory high entropy alloys has important research significance and application value. Summary of the invention

[0005] Based on the above background, the present invention proposes a new method for preparing NiCrNbMoTa refractory high entropy alloy using alloy raw materials. By accurately designing the composition of the cable welding wire and optimizing the surfacing process parameters, the high entropy alloy is prepared quickly, efficiently and at low cost, and a NiCrNbMoTa refractory high entropy alloy product with excellent performance is obtained.

[0006] The specific steps are as follows: A method for preparing a high entropy alloy using an alloy raw material, characterized in that the high entropy alloy is a NiCrNbMoTa refractory high entropy alloy; the specific steps are:

[0007] Step 1, twisting a high melting point metal wire or an alloy wire containing a high melting point metal, wherein the high melting point metal is one of Ni, Cr, Nb, Mo, and Ta, to obtain a refractory high entropy alloy cable welding wire; the central wire of the refractory high entropy alloy cable welding wire is a pure metal wire, and the peripheral wire is a bimetallic alloy wire nickel wire; wherein the central wire is 1, and the number of peripheral wires is an integer multiple of 4; the central wire is one of pure nickel wire, pure chromium wire, pure niobium wire, and pure molybdenum wire, and the peripheral wire is a bimetallic alloy wire of the metal element used for the central wire and the other four high melting point metals, and the number of peripheral wires of different metal elements is the same;

[0008] Step 2: Perform surfacing treatment on the refractory high entropy alloy cable welding wire in step 1 to obtain NiCrNbMoTa refractory high entropy alloy.

[0009] Preferably, the molar proportion of the metal element in the peripheral wire that is the same as that in the central wire is not less than 3%.

[0010] Preferably, the molar proportion of the metal element in the peripheral filaments that is the same as that in the central filaments is no more than 7%.

[0011] Preferably, the diameter of the central wire is 0.1-0.2 mm; the diameter of the peripheral wire is 0.5-0.75 mm;

[0012] Preferably, the number of peripheral wires in step 1 is 4 or 8.

[0013] Preferably, the surfacing technology uses TIG rotary wire arc welding additive technology.

[0014] Preferably, TIG rotary wire arc welding additive technology is used to perform cladding additive on the substrate using a refractory high entropy alloy cable welding wire.

[0015] Preferably, step 2 also includes placing the refractory high entropy alloy cable welding wire into a wire feeder, setting the wire feeding angle, wire feeding speed, additive speed, and using pure argon gas for protection.

[0016] Preferably, the wire feeding angle is 17-25°; the wire feeding speed is 5-10 mm / s; the additive speed is 150-200 mm / min; the welding current is 85-110 A; and the arc rotation rate is 200-250 r / min.

[0017] A NiCrNbMoTa refractory high entropy alloy is prepared by the method.

[0018] Beneficial effects:

[0019] Compared with the existing technology, the cable welding wire is more convenient to control the proportion of each metal. By controlling the metal type of the central wire and the percentage content of the central element in the peripheral wire, the proportion of different metal elements in the high entropy alloy can be conveniently adjusted.

[0020] The hardness and strength of high entropy alloys can be adjusted by adjusting the outer wire diameter, wire feeding angle during TIG welding, etc.

[0021] Furthermore, the method allows material addition with relatively low welding currents. DETAILED DESCRIPTION

[0022] Example 1: The specific steps of preparing NiCrNbMoTa refractory high entropy alloy using alloy raw materials are as follows:

[0023] Step 1: Preparation of refractory high entropy alloy cable welding wire

[0024] Material selection and size:

[0025] Center wire selection: A pure nickel wire with a diameter of 0.2mm is selected as the center wire.

[0026] Peripheral wire selection: Four bimetallic alloy wires are selected as peripheral wires, namely nickel-chromium alloy wire, nickel-niobium alloy wire, nickel-molybdenum alloy wire and nickel-tantalum alloy wire, one wire of each alloy wire, a total of 4 peripheral wires. In each alloy wire, the molar proportion of nickel is 3%, and the diameter is 0.6mm.

[0027] Twisting process:

[0028] Twist a central wire and four peripheral wires in a center-periphery arrangement, ensuring that the central wire is located in the center and the peripheral wires are evenly distributed around the central wire to form a cable structure. During the twisting process, ensure that the wires are in close contact with each other without looseness or misalignment.

[0029] Step 2: Surfacing

[0030] Equipment preparation:

[0031] Use TIG (tungsten inert gas) rotary wire arc welding additive technology and prepare TIG welding machine, wire feeder, argon gas protection device, etc.

[0032] Parameter settings:

[0033] Place the refractory high entropy alloy cable welding wire into the wire feeder, adjust the wire feeding angle to 25°, the wire feeding speed to 10 mm / s, and the material addition speed to 200 mm / min. The welding current is set to 85A, and the arc rotation rate is set to 200 r / min. Use pure argon gas for protection.

[0034] Surfacing operation:

[0035] Place the base material (such as stainless steel plate) on the welding platform, start the TIG welder, and perform surfacing according to the preset parameters.

[0036] The wire feeder feeds the refractory high entropy alloy cable wire into the welding area, and the arc rotates and melts the wire and the substrate surface to form a molten pool. With the continuous feeding of the wire and the increase of the substrate, the NiCrNbMoTa refractory high entropy alloy layer is gradually formed on the substrate.

[0037] Post-processing:

[0038] After surfacing is completed, the weld area is cooled to eliminate residual stress and improve organizational properties.

[0039] Perform necessary grinding and cleaning to remove spatter and oxides from the welding process.

[0040] Embodiment 2:

[0041] Compared with Example 1, the difference is that the molar proportion of nickel in the alloy wire in step 1 is 5%.

[0042] Embodiment 3:

[0043] Compared with Example 1, the difference is that the molar proportion of nickel in the alloy wire in step 1 is 7%.

[0044] Comparative Example 1

[0045] Compared with Example 1, the difference is that the molar proportion of nickel in the alloy wire in step 1 is 2%.

[0046] Comparative Example 2

[0047] Compared with Example 1, the difference is that the molar proportion of nickel in the alloy wire in step 1 is 8%.

[0048] Example 4

[0049] Compared with Example 2, the difference is that in step 1, the central wire is made of chromium element, and the four peripheral wires are respectively made of alloys consisting of chromium element and other four elements, and the molar proportion of chromium in each alloy wire is 5%.

[0050] Example 5

[0051] Compared with Example 2, the difference is that in step 1, the central wire is made of niobium element; the four peripheral wires are respectively made of alloys consisting of niobium element and other four elements, and the molar proportion of niobium in each alloy wire is 5%.

[0052] Example 6

[0053] Compared with Example 2, the difference is that in step 1, the central wire uses molybdenum element; the four peripheral wires respectively use alloys consisting of molybdenum element and other four elements, and the molar proportion of molybdenum in each alloy wire is 5%.

[0054] Comparative Example 3

[0055] Compared with Example 2, the difference is that in step 1, the central wire is made of tantalum element. The four peripheral wires are respectively made of alloys composed of tantalum element and other four elements, and the molar proportion of tantalum in each alloy wire is 5%.

[0056] Example 7

[0057] Compared with Example 5, the difference is that the molar proportion of niobium in the alloy wire in step 1 is 6%.

[0058] Example 8

[0059] Compared with Example 5, the difference is that the molar proportion of niobium in the alloy wire in step 1 is 7%.

[0060] Example 9

[0061] Compared with Example 5, the difference is that the diameter of the alloy wire in step 1 is 0.5 mm.

[0062] Example 10

[0063] Compared with Example 5, the difference is that the diameter of the alloy wire in step 1 is 0.75 mm.

[0064] Comparative Example 4

[0065] Compared with Example 5, the difference is that the diameter of the alloy wire in step 1 is 0.9 mm.

[0066] Embodiment 11

[0067] Compared with Example 5, the difference is that the wire feeding angle in step 2 is 20°.

[0068] Example 12

[0069] Compared with Example 5, the difference is that the wire feeding angle in step 2 is 17°.

[0070] Comparative Example 5

[0071] Compared with Example 5, the difference is that the wire feeding angle in step 2 is 14°.

[0072] Comparative Example 6

[0073] Compared with Example 5, the difference is that the wire feeding angle in step 2 is 28°.

[0074] The high entropy alloys obtained in the above examples and comparative examples were characterized in terms of micro-Vickers hardness, 750° yield strength, and thermal stability.

[0075] 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 Embodiment 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

[0076] The proportion of the central element in the peripheral alloy wire in the present application has a significant effect on Vickers hardness and yield strength. Within a certain range, as the molar proportion of the central element increases (such as Examples 1-3, 5, 7-8), its hardness and strength increase and are maintained at a high level. When the molar ratio of the central element is too low (such as Comparative Example 1), although the hardness of the material can be maintained at a high level, its yield strength and fracture strain are significantly reduced. When the molar ratio of the central element is too high (such as Comparative Example 2), the material still has a high level of fracture strain, but its yield strength and Vickers hardness are significantly reduced.

[0077] The technical solution of the present application can easily replace the central wire element, and then significantly adjust the molar proportion of different metal elements. At the same time, different elements selected for the central wire have different performances in terms of hardness, yield strength and fracture strain. According to the characterization results, when a metal element with a higher melting point is used as the central wire, the alloy finally obtained has different degrees of improvement in parameters such as hardness, yield strength and fracture strain. When tantalum is used as the central wire element (Comparative Example 3), it is found that there is no significant change in its hardness, but its fracture strain is significantly reduced.

[0078] The diameter of the outer alloy wire in the technical solution of this application has a certain influence on the yield strength and fracture strain of the metal. The outer wire diameter should be controlled within a certain range. When the diameter is too large (such as comparative example 4), the yield strength and fracture strain will be significantly reduced.

[0079] The wire feeding angle in the additive process in the technical solution of this application is also a key parameter. By reducing the wire feeding angle within a certain range, the strength of the material can be improved. However, when the wire feeding angle is too small (such as in Comparative Example 5), the hardness of the material drops sharply; when the wire feeding angle is too large (such as in Comparative Example 6), the yield strength and fracture strain of the material are significantly reduced.

Claims

1. A method for preparing a high entropy alloy using an alloy raw material, characterized in that: The high entropy alloy is a NiCrNbMoTa refractory high entropy alloy; the specific steps are: Step 1, twisting a high melting point metal wire or an alloy wire containing a high melting point metal, wherein the high melting point metal is one of Ni, Cr, Nb, Mo, and Ta, to obtain a refractory high entropy alloy cable welding wire; the central wire of the refractory high entropy alloy cable welding wire is a pure metal wire, and the peripheral wire is a bimetallic alloy wire nickel wire; The number of the central wire is 1, and the number of the peripheral wires is an integer multiple of 4; the central wire is one of pure nickel wire, pure chromium wire, pure niobium wire, and pure molybdenum wire; the peripheral wires are bimetallic alloy wires of the metal element used in the central wire and the other four high-melting-point metals, and the number of peripheral wires composed of different metal elements is the same; Step 2: Perform surfacing treatment on the refractory high entropy alloy cable welding wire in step 1 to obtain NiCrNbMoTa refractory high entropy alloy.

2. According to the method for preparing a high entropy alloy using an alloy raw material as described in claim 1, the molar proportion of the metal element in the peripheral wire that is the same as the element in the central wire is not less than 3%.

3. According to the method for preparing a high entropy alloy using an alloy raw material as described in claim 2, the molar proportion of the metal element in the peripheral wire that is the same as the element in the central wire is no more than 7%.

4. According to the method for preparing a high entropy alloy using an alloy raw material as described in claim 1, the diameter of the central wire is 0.1-0.2 mm; the diameter of the peripheral wire is 0.5-0.75 mm.

5. According to the method for preparing a high entropy alloy using an alloy raw material as claimed in claim 1, the number of peripheral wires in step 1 is 4 or 8.

6. According to the method for preparing a high entropy alloy using an alloy raw material as claimed in claim 1, the surfacing technology adopts TIG rotating wire arc welding additive technology.

7. According to the method for preparing a high entropy alloy using an alloy raw material according to claim 6, a refractory high entropy alloy cable welding wire is used to perform cladding additive on a substrate using TIG rotary wire arc welding additive technology.

8. According to the method for preparing a high entropy alloy using an alloy raw material according to claim 7, step 2 also includes placing the refractory high entropy alloy cable welding wire into a wire feeder, setting the wire feeding angle, wire feeding speed, and material addition speed, and using pure argon gas for protection.

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

10. A NiCrNbMoTa refractory high entropy alloy prepared by the method according to any one of claims 1 to 9.