WO2023142863A1 - 基于扩散多元节技术的沉淀强化高熵合金成分设计和制备方法 - Google Patents

基于扩散多元节技术的沉淀强化高熵合金成分设计和制备方法 Download PDF

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WO2023142863A1
WO2023142863A1 PCT/CN2022/143125 CN2022143125W WO2023142863A1 WO 2023142863 A1 WO2023142863 A1 WO 2023142863A1 CN 2022143125 W CN2022143125 W CN 2022143125W WO 2023142863 A1 WO2023142863 A1 WO 2023142863A1
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diffusion
precipitation
alloy
entropy alloy
content
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French (fr)
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蔡格梅
张顺心
黄兴明
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中南大学
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C22C30/02—Alloys containing less than 50% by weight of each constituent containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working

Definitions

  • the invention utilizes diffusion multi-element technology to carry out component design and preparation process of precipitation strengthening high-entropy alloys, and belongs to the field of high-entropy alloys.
  • high-entropy alloys are different from traditional alloys that are dominated by one element. It has no distinction between primary and secondary elements. So far, four effects have been summarized for high-entropy alloys: high-entropy effect, lattice distortion effect, slow diffusion effect and "cocktail" effect. At the same time, high-entropy alloys have attracted widespread attention due to their good corrosion resistance, radiation resistance and high temperature stability, as well as three single-phase solid solution structures of FCC, BCC and HCP. High-entropy alloys with FCC structure have excellent ductility, but their low strength limits their application in engineering fields.
  • compositional design of precipitation-strengthened high-entropy alloys has become a current research hotspot. It has almost unlimited possibilities in alloy composition design, but it also brings us greater challenges in composition selection.
  • a variety of precipitation-strengthened high-entropy alloys have been developed. For example, (FeCoNi) 92 Al 2.5 Ti 5.5 precipitation-strengthened FCC high-entropy alloys have been designed by the CALPHAD method; based on the overall valence electron concentration (OVEC) design strategy, prepared Ni 2 CoCrFeNb 0.15 Precipitation Strengthened High Entropy Alloys. But these are not universally applicable to the design of precipitation-strengthened high-entropy alloys, and its general design method is still vague.
  • the technology based on diffusion multi-element joints or diffusion couples has unique advantages in studying phase composition, phase stability and phase distribution in a large composition range, which can greatly speed up the design process of precipitation-strengthened high-entropy alloys.
  • This method can obtain information such as phase stability more quickly and effectively than traditional alloy production design, and use the obtained composition and phase distribution curves to accelerate the development of precipitation-strengthened high-entropy alloys.
  • the present invention proposes a new strategy for high-throughput screening of precipitation-strengthened high-entropy alloy components and a corresponding mechanical heat treatment process for the designed alloy based on the diffusion multi-component technology.
  • the present invention is based on the design of the precipitation strengthening high-entropy alloy composition and its preparation process based on the diffusion multi-component technology.
  • the composition of the diffusion layer in the couple is screened for the preparation of precipitation-strengthened high-entropy alloy matrix components.
  • heat treatment is performed on the candidate high-entropy single-phase solid solution alloy to obtain a precipitation-strengthened high-entropy alloy product with excellent performance.
  • composition design method of precipitation strengthening high entropy alloy based on diffusion multiple joint technology of the present invention comprises the following steps:
  • Step A Prepare the diffused multi-element joint and perform annealing
  • the alloy is a high-entropy alloy or a medium-entropy alloy block; at least two of the prepared N kinds of alloy blocks are placed together according to the requirements of the diffusion multi-element joint, Carry out annealing experiment; obtain a single-phase solid solution diffusion layer; among the two alloys in contact with each other in the diffusion joint, the number of constituent elements of one alloy is S 1 , and the number of constituent elements of the other alloy is S 2 , 0 ⁇
  • the types and amounts of at least two elements are consistent; the amount here is preferably a molar amount;
  • the two alloy blocks that are in contact are defined as A and B respectively; the elements of different types in A and B are defined as A1, A2...An; B1, B2...Bp, and n and p are positive integers;
  • Step B Obtain the composition range of the precipitation-strengthened high-entropy alloy
  • composition of the diffusion layer corresponding to each group of diffusion couples obtained after the annealing experiment in step A is tested by electron probe technology; based on the test results, the content range of each element in the diffusion layer is obtained, and the Ai element is found in the test results and the intersection point of Bj element; and obtain the content of other elements corresponding to the intersection point of Ai element and Bj element in the diffusion layer; then perform an error correction of ⁇ 1.5 on the basis of the content of each element; obtain the composition of the precipitation-strengthened high-entropy alloy Range; the Ai is selected from an element in A1, A2...An; the Bj is selected from an element in B1, B2...Bp.
  • the difference between the constituent elements of the phase-contact high-entropy alloy is greater than 2, it will be difficult to obtain useful information, which will lead to unusable follow-up test results; and then the experiment fails.
  • the present invention is based on the composition design method of precipitation strengthening high-entropy alloys based on diffusion multi-joint technology.
  • the two alloys in contact with each other in the diffusion couple at least 3 elements are used in both alloys, and the corresponding elements are in The molar content is equal in different alloys.
  • the present invention is based on the method for designing the composition of precipitation-strengthened high-entropy alloys based on diffusion multi-joint technology.
  • the two alloys that are in contact with each other in the diffusion couple one element is different, and the types of other elements are the same; and the corresponding elements are in different alloys.
  • the molar content is equal.
  • n is a positive integer less than or equal to 2. 1 is more preferable.
  • p is a positive integer less than or equal to 2. 1 is more preferable.
  • the present invention provides necessary conditions for fast acquisition of useful information by constraining the values of n and p, and also provides necessary conditions for subsequent rapid acquisition of precipitation-strengthened high-entropy alloy components.
  • one alloy has at least less surface contact than the other three alloys.
  • the surface contact here is relative to the point contact. That is, there is a clear contact surface.
  • the present invention is based on the composition design method of the precipitation strengthening high-entropy alloy based on the diffusion multi-joint technology
  • the high-entropy alloy is composed of at least four elements of Co, Cr, Fe, Ni, Al, Cu, Hf, Zr, Nb, Ta, W, Mo, V, Si, rare earth elements and Ti;
  • the medium entropy alloy is composed of at least three elements in Co, Cr, Fe, Ni, Al, Cu, Hf, Zr, Nb, Ta, W, Mo, V, Si, Sc, rare earth elements and Ti ;
  • the rare earth element is selected from at least one of Gd, Tb, Dy, Ho, Er.
  • A-B 0.
  • the present invention is based on the precipitation strengthening high-entropy alloy composition design method based on diffusion multi-joint technology, using Co, Cr, Fe, Ni, Al, V, Mo, Nb, Hf, Ta, Si, Cu and Ti metals as raw materials , the purity of raw materials is not less than 99.9%;
  • Nine high-entropy alloy ingots of CoCrFeNiV, CoCrFeNiMo, CoCrFeNiCu, CoCrFeNiTi, CoCrFeNiAl, CoCrFeNiNb, CoCrFeNiHf, CoCrFeNiTa, CoCrFeNiSi are prepared in non-consumable arc melting; Blocks required for multi-element joints; assembled into diffuse multi-element joints and annealed at 1050°C ⁇ 1150°C for 168h-240h;
  • Operations to obtain the composition of precipitation-strengthened high-entropy alloys include:
  • composition of the diffusion layer produced by the diffusion annealing of the two alloys in contact with each other in the diffusion multi-element joint is tested by electron probe technology
  • Extension methods include:
  • the two alloys that are in contact with each other in the diffusion multi-section as FG and FH; where F is composed of at least 2 elements; G and H are different elements (preferably in the same amount); after diffusion annealing, the content is the ordinate , take the diffusion distance as the abscissa; find the intersection point of G and H content, and obtain the content of other elements corresponding to the intersection point of G element and H element in the diffusion layer; then perform ⁇ 1 based on the content of each element
  • the error correction of the composition of precipitation strengthening high entropy alloy is obtained.
  • the composition design method of the precipitation strengthening high-entropy alloy based on the diffusion multi-section technology of the present invention when the alloys in surface contact are CoCrFeNiAl alloy and CoCrFeNiTi alloy, in the diffusion layer formed by the diffusion of CoCrFeNiAl and CoCrFeNiTi, the content is the ordinate, and the diffusion distance is As the abscissa, find the intersection point of Al and Ti content, and obtain the content of other elements corresponding to the intersection point of Al element and Ti element in the diffusion layer; then perform ⁇ 1 error correction on the basis of the content of each element,
  • the precipitation-strengthened high-entropy alloy composition is obtained as Co x1 Cr x2 Fe x3 Ni x4 Al x5 Ti x6 , where x1, x2, x3, x4, x5, and x6 are the atomic percentages of the corresponding elements; and 23 ⁇ x1 ⁇ 25, 20 ⁇ x2 ⁇ 22, 24 ⁇
  • the alloys in contact are CoCrFeNiCu alloy and CoCrFeNiTi alloy
  • the diffusion layer formed by the diffusion of CoCrFeNiCu and CoCrFeNiTi take the content as the ordinate and the diffusion distance as the abscissa, find the intersection point of Cu and Ti content, and obtain The content of other elements corresponding to the intersection point of Cu element and Ti element in the diffusion layer; then, based on the content of each element, an error correction of ⁇ 1 is performed to obtain the precipitation strengthening high-entropy alloy composition Co y1 Cr y2 Fe y3 Ni y4 Cu y5 Ti y6 , where y1, y2, y3, y4, y5, y6 are the atomic percentages of the corresponding elements, and 22 ⁇ y1 ⁇ 24, 18 ⁇ y2 ⁇ 20, 22 ⁇ y3 ⁇ 24, 24 ⁇ y4 ⁇ 26, 4 ⁇ y5 ⁇ 6, 4 ⁇ y6 ⁇ 6.
  • the present invention is based on the method for designing the composition of the precipitation-strengthened high-entropy alloy matrix based on the diffusion multi-section technology.
  • the purity of the raw material is not less than 99.9%. 3-9mm.
  • the composition of the diffusion layer obtained by CoCrFeNiAl-CoCrFeNiTi diffusion changes from Co 24 Cr 20 Fe 23.4 Ni 25.5 Al 5.4 Ti 1.7 to Co 23 Cr 22 Fe 23.4 Ni 21.6 Al 0.4 Ti 9.6 ;
  • CoCrFeNiCu-CoCrFeNiTi diffusion The composition of the diffusion layer varies from Co 22.4 Cr 19.6 Fe 23.5 Ni 23 Cu 10 Ti 1.5 to Co 22.2 Cr 20.8 Fe 22.7 Ni 22.9 Cu 0.8 Ti 10.6 .
  • the present invention selects the precipitation strengthening high-entropy alloy composition point on the curve with the same values of Al and Ti, Cu and Ti, and the chemical formula is Co 24 Cr 20.9 Fe 25.1 Ni 24 Al 3 Ti 3 and Co 22.8 Cr 19 Fe 23.5 Ni 24.7 Cu 5 Ti 5 . Due to the error of instrument measurement, the value on the measured composition curve is corrected by ⁇ 1 error, so 23 ⁇ x1 ⁇ 25, 20 ⁇ x2 ⁇ 22, 24 ⁇ x3 ⁇ 26, 23 ⁇ x4 ⁇ 25, 2 ⁇ x5 ⁇ 4. 2 ⁇ x6 ⁇ 4, 22 ⁇ y1 ⁇ 24, 18 ⁇ y2 ⁇ 20, 22 ⁇ y3 ⁇ 24, 24 ⁇ y4 ⁇ 26, 4 ⁇ y5 ⁇ 6, 4 ⁇ y6 ⁇ 6.
  • the preparation method of the precipitation-strengthened high-entropy alloy described in the present invention rapidly screens and obtains different precipitation-strengthened high-entropy alloy matrix components according to the diffusion couples of the multi-component diffusion joints, and prepares various raw materials; prepares in non-consumable arc melting, and obtains high-entropy alloys.
  • the chemical formula of the precipitation-strengthened high-entropy alloy obtained after screening is: Co x1 Cr x2 Fe x3 Ni x4 Al x5 Ti x6 or Co y1 Cr y2 Fe y3 Ni y4 Cu y5 Ti y6 , according to the corresponding chemical formula, with Co, Cr, Fe, Ni, Al, Cu and Ti metals; Co x1 Cr x2 Fe x3 Ni x4 Al x5 Ti x6 and Co y1 are prepared in non-consumable arc melting Cr y2 Fe y3 Ni y4 Cu y5 Ti y6 ; followed by homogenization treatment and cold rolling of the cast ingot; finally solid solution and aging treatment of the cold-rolled sample after vacuum sealing.
  • the homogenization temperature is 1000-1200°C, and the time is 12h-24h; as a preferred solution, the homogenization temperature is 1100°C, and the holding time is 20h;
  • the deformation in a single pass is 5%-10%, and the total deformation is 60%-80%; as an optimal solution: the deformation in a single pass is 5%, and the total deformation is 70%;
  • Vacuum sealing pressure is 0.3bar-0.5bar
  • the solution treatment temperature is 1000°C-1200°C, and the time is 4min-10min;
  • the aging treatment temperature is 600°C-900°C, and the time is 8h-50h.
  • the obtained Co x1 Cr x2 Fe x3 Ni x4 Al x5 Ti x6 and Co y1 Cr y2 Fe y3 Ni y4 Cu y5 Ti y6 are all FCC high-entropy alloys; and face centered cubic L1 2 structure ⁇ ' nano-precipitated particles uniformly distributed on the substrate.
  • the invention Compared with the single-phase FCC high-entropy alloy, the invention has greatly improved product strength and good plasticity.
  • the diffusion multi-component technology is successfully applied to the composition design of precipitation-strengthened high-entropy alloys, which opens up a new direction for the design of precipitation-strengthened high-entropy alloys.
  • the present invention can perform high-throughput screening of components.
  • the invention can efficiently obtain useful data; the composition range of the precipitation-strengthened high-entropy alloy can be quickly obtained based on the analysis of the useful data.
  • both the data acquisition method and the data analysis method are original.
  • composition design of precipitation-strengthened high-entropy alloys based on diffusion multi-joint technology has the characteristics of short process, material saving and general practical effect.
  • the designed alloy has a uniform and fine structure, and at the same time, a large number of uniformly distributed nano-precipitated strengthening particles are precipitated on the matrix, and a precipitate with good strength and plasticity is obtained.
  • the present invention based on the rapid screening precipitation strengthening high-entropy alloy matrix alloy technology of diffusion multi-component, successfully prepared Co x1 Cr x2 Fe x3 Ni x4 Al x5 Ti x6 and Co y1 Cr y2 Fe y3 Ni y4 Cu y5 Ti y6 A representative precipitation-strengthened high-entropy alloy with an excellent combination of strength and ductility.
  • Fig. 1 is a structural design diagram of the diffusion multi-element section in the specific embodiment 1.
  • A CoCrFeNiV
  • B CoCrFeNiMo
  • C CoCrFeNiCu
  • D CoCrFeNiTi
  • E CoCrFeNiAl
  • F CoCrFeNiNb
  • G CoCrFeNiHf
  • H CoCrFeNiTa
  • I CoCrFeNiSi.
  • Figure 2 is a microstructure diagram of the CoCrFeNiAl-CoCrFeNiTi diffusion layer region in the diffusion multi-component joint.
  • Fig. 3 is a microstructure diagram of the CoCrFeNiCu-CoCrFeNiTi diffusion layer region in the diffusion multi-component joint.
  • Figure 4 (a) is the component concentration curve of Al and Ti diffusion layer in the multi-diffusion joint of Example 1; (b) is the component concentration curve of Cu and Ti diffusion layer in the multi-diffusion joint of Example 1.
  • Figure 5(a)(b) is the SEM image of the microstructure of the precipitation-strengthened high-entropy alloy (700°C/8h) prepared in Example 2 under different magnifications, and the uniformly distributed nano-precipitated particles on the matrix can be seen.
  • Fig. 6 is the tensile engineering stress-strain curve of the precipitation-strengthened high-entropy alloy prepared in Example 2 after different aging temperatures.
  • Figure 7(a)(b) is the SEM image of the microstructure of the precipitation-strengthened high-entropy alloy (700°C/8h) prepared in Example 3 at different magnifications. There are a large number of spherical nano-precipitated particles evenly distributed on the matrix.
  • Fig. 8 is a graph of tensile engineering stress-strain curves of the precipitation-strengthened high-entropy alloy prepared in Example 3 after different aging temperatures.
  • Fig. 9 is a microstructure diagram of CoCrFeNiAlCu-CoCrFeNiAlTi region obtained by diffusion.
  • Fig. 10 is the tensile engineering stress-strain curve of the Co 20 Cr 16 Fe 32.5 Ni 17.5 Al 4 Cu 3 Ti 7 precipitation-strengthened high-entropy alloy prepared in Example 4 after solution treatment and different aging temperatures.
  • the purity of the metal raw materials used in the following examples is not less than 99.9%.
  • the alloy ingots were smelted for 1 min each time, smelted repeatedly 5 times, and taken out after cooling; the CoCrFeNiX block ingots of a certain size were obtained by wire electric discharge cutting, and polished and cleaned.
  • Step 2 Prepare nickel sheath and sheath cover. Assemble the CoCrFeNiX alloy block into the sheath according to the assembly method shown in Figure 1.
  • the cover is welded to the upper and lower ends of the cover by vacuum electron beam welding. Hot isostatic pressing is then used to bring the alloy blocks into intimate contact.
  • the welding depth of vacuum electron beam welding is 1.5 ⁇ 2mm
  • the hot isostatic pressing parameters are: 980-1020°C, 5-7h/130-170Mpa.
  • Diffusion annealing (1050-1150°C/10-20ds) was performed on the prepared diffusion multi-component at a set temperature.
  • Step 3 Use an electron probe to test the composition of the diffusion layer in the diffusion couple. Remove the fixture and polish the oxide skin at the same time; inlay the diffusion couple with phenolic plastic powder; prepare the electronic probe test sample by mechanical polishing; use the electronic probe to test the elemental composition of the diffusion layer.
  • the composition curve is drawn: it is found that the CoCrFeNiAl-CoCrFeNiTi diffusion joint forms a diffusion layer of more than 100 microns (as shown in Figure 2), and the contents of Co, Cr, Fe, and Ni elements in the diffusion layer do not change much, only Al and Ti There are major changes.
  • the CoCrFeNiCu-CoCrFeNiTi diffusion joint forms a diffusion layer of more than 100 microns (as shown in Figure 3). The contents of Co, Cr, Fe, and Ni elements in the diffusion layer do not change much, and only Cu and Ti have large changes.
  • Step 1 According to the composition curve of the CoCrFeNiAl-CoCrFeNiTi diffusion couple (as shown in Figure 4a), the composition of the solid solution region of the diffusion layer changes from Co 24 Cr 20 Fe 23.4 Ni 25.5 Al 5.4 Ti 1.7 to Co 23 Cr 22 Fe 23.4 Ni 21.6 Al 0.4 Ti 9.6 , can be used as candidate components of Co x1 Cr x2 Fe x3 Ni x4 Al x5 Ti x6 precipitation strengthening high entropy alloys.
  • the composition point on the curve with the same value of Al and Ti is selected here, the chemical formula is Co 24 Cr 20.9 Fe 25.1 Ni 24 Al 3 Ti 3 , where x1, x2, x3, x4, x5, x6 are the corresponding elements Due to the error of instrument measurement, the value on the measured composition curve is corrected by ⁇ 1 error, so 23 ⁇ x1 ⁇ 25, 20 ⁇ x2 ⁇ 22, 24 ⁇ x3 ⁇ 26, 23 ⁇ x4 ⁇ 25, 2 ⁇ x5 ⁇ 4, 2 ⁇ x6 ⁇ 4.
  • Step 2 Prepare 100 g of Co 24 Cr 20.9 Fe 25.1 Ni 24 Al 3 Ti 3 raw materials according to the corresponding composition ratio; prepare in a vacuum non-consumable arc melting furnace, each melting time is 1 min, and repeat melting for more than 5 times; In the Fu furnace, the ingot was homogenized at 1100°C for 12 hours in an argon atmosphere, and then quenched in water; the alloy was cold-rolled with a 70% thinning rate, and the reduction in each pass was 5%; °C solid solution for 6 minutes, aging at 600, 700 and 800 °C for 8 hours respectively.
  • Step 3 Analyzing the alloy structure by scanning electron microscopy, it was found that a large number of L1 2 structure nanoscale precipitates were evenly distributed on the matrix, as shown in Figure 5 .
  • Step 4 Cut the dog bone sample by EDM, and use the MTS experimental machine to carry out the tensile test at room temperature with a strain rate of 1.4*10 -3 s -1 ; the tensile engineering stress-strain curve obtained from the test is shown in Figure 6
  • the yield strength is 759MPa
  • the tensile strength is 1193MPa
  • the elongation is 26%
  • the grain size is 4.5 ⁇ m
  • the yield strength is 851MPa
  • the tensile strength is 1281MPa
  • the elongation 30%
  • the grain size is 7.2 ⁇ m
  • the yield strength is 685MPa
  • the tensile strength is 1081MPa
  • the elongation rate was 33%
  • the grain size was 9.1 ⁇ m.
  • Step 1 According to the composition curve of the CoCrFeNiCu-CoCrFeNiTi diffusion couple (as shown in Figure 4b), the composition of the solid solution region of the diffusion layer changes from Co 22.4 Cr 19.6 Fe 23.5 Ni 23 Cu 10 Ti 1.5 to Co 22.2 Cr 20.8 Fe 22.7 Ni 22.9 Cu 0.8 Ti 10.6 , can be used as candidate components of Co y1 Cr y2 Fe y3 Ni y4 Cu y5 Ti y6 precipitation strengthening high entropy alloys.
  • the composition points on the curve where Cu and Ti have the same value are selected here, and the chemical formula is Co 22.8 Cr 19 Fe 23.5 Ni 24.7 Cu 5 Ti 5 , where y1, y2, y3, y4, y5, and y6 are the corresponding elements Due to the error of instrument measurement, the value on the measured composition curve is corrected by ⁇ 1 error, so 22 ⁇ y1 ⁇ 24, 18 ⁇ y2 ⁇ 20, 22 ⁇ y3 ⁇ 24, 24 ⁇ y4 ⁇ 26, 4 ⁇ y5 ⁇ 6, 4 ⁇ y6 ⁇ 6.
  • Step 2 Prepare 100 g of Co 22.8 Cr 19 Fe 23.5 Ni 24.7 Cu 5 Ti 5 raw materials according to the corresponding composition ratio; prepare in a vacuum non-consumable arc melting furnace, each melting time is 1 min, and repeat melting for more than 5 times; In the Fu furnace, the ingot was homogenized at 1100°C for 12 hours in an argon atmosphere, and then quenched in water; the alloy was cold-rolled with a 70% thinning rate, and the reduction in each pass was 5%; °C solid solution for 6 minutes, aging at 600, 700 and 800 °C for 8 hours respectively.
  • Step 3 Analyzing the alloy structure by scanning electron microscope, it is found that a large number of L1 2 structure nanoscale precipitates are uniformly distributed on the matrix, as shown in Figure 7 .
  • Step 4 Cut the dog bone sample by EDM, and use the MTS experimental machine to conduct the tensile test at room temperature with a strain rate of 1.4*10 -3 s -1 ; the tensile engineering stress-strain curve obtained from the test is shown in Figure 8 As shown, when the aging temperature is 600°C and the aging time is 8h, the yield strength is 758MPa, the tensile strength is 1072MPa, the elongation is 18%, and the grain size is 6.6 ⁇ m; when the aging temperature is 700°C, the aging time is At 8h, the yield strength is 1020MPa, the tensile strength is 1339MPa, the elongation is 19%, and the grain size is 8.1 ⁇ m; when the aging temperature is 800°C and the aging time is 8h, the yield strength is 738MPa, and the tensile strength is 1160MPa , the elongation rate was 21%, and the grain size was 10.2 ⁇ m.
  • Step 1 According to the test results, it was found that the CoCrFeNiAlCu-CoCrFeNiAlTi diffusion region formed a diffusion layer of more than 100 microns (as shown in Figure 9a). According to the composition curve of the CoCrFeNiAlCu-CoCrFeNiAlTi diffusion zone (as shown in Figure 9b), the composition of the solid solution zone of the diffusion layer changes continuously from Co 19.5 Cr 17.1 Fe 33.8 Ni 17.1 Al 3.6 Cu 1.5 Ti 7.4 to Co 19.5 Cr 15.7 Fe 30.9 Ni 17.8 Al 4.4 Cu 5.1 Ti 6.7 can be used as candidate components of Co y1 Cr y2 Fe y3 Ni y4 Al y5 Cu y6 Ti y7 precipitation strengthened high-entropy alloys.
  • the composition point Co 20 Cr 16 Fe 32.5 Ni 17.5 Al 4 Cu 3 Ti 7 on the curve is selected here, where y1, y2, y3, y4, y5, y6, and y7 are the atomic percentages of the corresponding elements. Due to the There is an error in the measurement, and the value on the measured composition curve is corrected by ⁇ 1 error, so 19 ⁇ y1 ⁇ 20, 15.5 ⁇ y2 ⁇ 17.5, 30 ⁇ y3 ⁇ 34, 17 ⁇ y3 ⁇ 18, 3 ⁇ y4 ⁇ 5, 1.5 ⁇ y5 ⁇ 5.5, 6 ⁇ y6 ⁇ 8.
  • Step 2 Prepare 100 g of Co 20 Cr 16 Fe 32.5 Ni 17.5 Al 4 Cu 3 Ti 7 raw materials according to the corresponding composition ratio; prepare in a vacuum non-consumable arc melting furnace, each melting time is 1 min, and repeat melting more than 5 times; In the muffle furnace, the ingot was homogenized at 1100°C for 12 hours in an argon atmosphere, and then quenched in water; the alloy was cold-rolled with a reduction rate of 70%, and the reduction in each pass was 5%; Solid solution at 1100°C for 6 minutes, aging at 600, 700, and 800°C for 8 hours respectively.
  • Step 3 Cut the dog bone sample by EDM, and use the MTS experimental machine to conduct the tensile test at room temperature with a strain rate of 1.4*10 -3 s -1 ; the tensile engineering stress-strain curve obtained from the test is shown in Figure 8 As shown, when the aging temperature is 600°C and the aging time is 8h, the yield strength is 1030MPa, the tensile strength is 1412MPa, and the elongation is 27%; when the aging temperature is 700°C and the aging time is 8h, the yield strength is 1004MPa , the tensile strength is 1508MPa, and the elongation is 26%; when the aging temperature is 800°C and the aging time is 8h, the yield strength is 659MPa, the tensile strength is 1195MPa, and the elongation is 24%.
  • the present invention utilizes the diffusion information of different CoCrFeNiX-CoCrFeNiY and CoCrFeNiXY-CoCrFeNiXZ alloy groups to realize the rapid screening of the composition range of the precipitation-strengthened high-entropy alloy solid solution.
  • the reliability of this method by selecting a certain component in the candidate interval screened by diffusion, through subsequent appropriate mechanical heat treatment, a nano-scale strengthening phase uniformly distributed on the matrix was obtained, and two new types of high-performance Co x1 were successfully developed.

Abstract

本发明利用扩散多元节技术进行新型沉淀强化高熵合金的快速设计与制备，属于高熵合金领域。本发明将高熵合金和/或中熵合金制备为扩散多元节；然后进行扩散实验，得到单相固溶体扩散层；对扩散层成分进行测试，得出该扩散层中各元素的含量范围；根据该扩散层中各元素的含量范围和种类设计得到沉淀强化高熵合金成分；选取基于高通量筛选得到沉淀强化高熵合金区域典型成分进行合金熔炼、均匀化处理、冷轧、固溶、时效处理，制备得到具有优异强度和塑性结合的沉淀强化高熵合金。本发明率先利用扩散多元节技术对沉淀强化高熵合金的成分区间进行快速筛选，并制备了性能优越的新产品。这为沉淀强化高熵合金的快速设计提供了新的思路，并为其产业化提供了必要条件。

Description

基于扩散多元节技术的沉淀强化高熵合金成分设计和制备方法 技术领域
本发明利用扩散多元节技术进行沉淀强化高熵合金的成分设计及其制备工艺，属于高熵合金领域。
 背景技术
高熵合金作为十几年前提出的一种新型合金材料，与以一种元素为主的传统合金有所不同，它没有主、次元素之分。到目前为止，高熵合金已被总结出四大效应：高熵效应、晶格畸变效应、缓慢扩散效应和“鸡尾酒”效应。同时高熵合金由于良好的耐腐蚀性、抗辐照性和高温稳定性以及FCC、BCC和HCP三种单相固溶体结构而受到人们广泛关注。FCC结构的高熵合金具有优异的延展性，但是其较低的强度限制了在工程领域的应用。目前，已有多种方法用于增强FCC高熵合金，其中的沉淀强化可以在提高强度的同时保证一定塑性，具有独特的优势。基于目前高熵合金成分设计参考的混合焓ΔHmix、混合熵ΔSmix、原子尺寸和价电子浓度VEC等参数，和对多主元固溶体相形成的ΔHmix-δ准则、VEC判据和Ω准则等，难以进行沉淀强化高熵合金的设计。
 技术问题
沉淀强化高熵合金的成分设计成为目前的研究热点。其在合金成分设计上几乎具有无限可能性，但这也在成分选择上面给我们带来了更大的挑战。目前已有多种沉淀强化高熵合金被研发出来，例如，通过CALPHAD方法设计出(FeCoNi) 92Al 2.5Ti 5.5沉淀强化FCC高熵合金；基于总体价电子浓度（OVEC）的设计策略，制备出的的Ni 2CoCrFeNb 0.15沉淀强化高熵合金。但是这些并不普遍适用与沉淀强化高熵合金设计，它的通用设计方法还很模糊。
基于扩散多元节或扩散偶技术在大的成分范围内研究相成分、相稳定性和相分布方面有独特的优势，可以大大加快沉淀强化高熵合金设计过程。这种方法可以比传统合金生产设计更加快速有效的获得相稳定性等信息，利用得到的成分和相分布的曲线图，加速沉淀强化高熵合金的开发。但针对高熵合金，如何利用扩散多元节或扩散偶技术获得相稳定性等有用信息进而利用成分和相分布的曲线图，加速沉淀强化高熵合金的开发，还鲜有报道。
 技术解决方案
针对目前沉淀强化高熵合金成分设计存在的问题，本发明基于扩散多元节技术，提出高通量进行沉淀强化高熵合金成分筛选的新策略和所设计的合金进行的相应机械热处理工艺。
       本发明基于扩散多元节技术的沉淀强化高熵合金成分设计及其制备工艺，通过制备高熵合金-高熵合金扩散多元节或高熵合金-中熵合金的扩散多元节，根据任一组扩散偶中扩散层成分，筛选用于制备沉淀强化高熵合金基体成分。然后再对候选高熵单相固溶体合金进行热处理，得到性能优异的沉淀强化高熵合金产品。
本发明基于扩散多元节技术的沉淀强化高熵合金成分设计方法，包括下述步骤：
步骤A制备扩散多元节并进行退火
制备至少N种合金块体，所述合金为高熵合金或中熵合金块体；将所制备的N种合金块体中至少2种，按扩散多元节的要求将合金块体放置在一起，进行退火实验；得到单相固溶体扩散层；扩散节中相接触的两种合金中，一种合金的组成元素的种类数为S 1、另外一种合金的组成元素的种类数为S 2，0≤|S 1-S 2|≤2；所述N为大于等于2的正整数；
扩散偶中相接触的两种合金中，至少有两种元素的种类和用量一致；此处的用量优选为摩尔用量；
定义相接触的两种合金块体分别为A、B；A、B中种类不相同的元素定义为A1、A2….An；B1、B2….Bp，所述n、p为正整数；
元素定义时，按照一种元素一个符号的方式进行；
步骤B、获取沉淀强化高熵合金成分范围
通过电子探针技术对步骤A中退火实验后所得每一组扩散偶所对应的扩散层成分进行测试；基于测试结果，得出该扩散层中各元素的含量范围，在测结果中找到Ai元素和Bj元素的交叉点；并获取扩散层中Ai元素和Bj元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1.5的误差修正；得到沉淀强化高熵合金成分范围；所述Ai选自A1、A2….An中的一种元素；所述Bj选自B1、B2….Bp中的一种元素。
在本发明中，若相接触高熵合金的组成元素种类相差大于2则很难获取到有用信息，这会导致后续测试结果无法利用；进而实验失败。
在本发明中若不能得到单相固溶体扩散层，则也很难获得有用信息，这也会导致后续测试结果无法利用；进而实验失败。
作为优选方案，本发明基于扩散多元节技术的沉淀强化高熵合金成分设计方法，扩散偶中相接触的两种合金中，至少有3种元素在二种合金中均用到，且对应元素在不同合金中的摩尔含量相等。
作为优选方案，本发明基于扩散多元节技术的沉淀强化高熵合金成分设计方法，扩散偶中相接触的两种合金中，有一种元素不同，其他元素的种类一致；且对应元素在不同合金中的摩尔含量相等。
作为优选，n为小于等于2的正整数。进一步优选为1。
作为优选，p为小于等于2的正整数。进一步优选为1。
本发明通过对n、p值的约束，为实现有用信息快速获取提供了必要条件，也为后续快速得到沉淀强化高熵合金成分提供了必要条件。
为了快速进行高通量实验，按扩散多元节的要求放置在一起，进行退火实验时，一种合金至少于其他三种合金存在面接触。这里的面接触是相对于点接触而言的。即存在明显的接触面。
作为优选方案，本发明基于扩散多元节技术的沉淀强化高熵合金成分设计方法，
步骤A中，所述高熵合金由Co、Cr、Fe、Ni、Al、Cu、Hf、Zr、Nb、Ta、W、Mo、V、Si、稀土元素和Ti中至少四种元素构成；
步骤A中，所述中熵合金由Co、Cr、Fe、Ni、Al、Cu、Hf、Zr、Nb、Ta、W、Mo、V、Si、Sc、稀土元素和Ti中至少三种元素构成；
所述稀土元素选自Gd、Tb、Dy、Ho、Er中的中至少一种。
作为更进一步的优选方案，A-B=0。扩散节中相接触的两种合金中的组元种类一致，且只有一种元素不同但摩尔含量相同时，其能最快获取一维有用数据。
作为优选方案，本发明基于扩散多元节技术的沉淀强化高熵合金成分设计方法，以Co、Cr、Fe、Ni、Al、V、Mo、Nb、Hf、Ta、Si、Cu和Ti金属作为原料，原料的纯度不低于99.9%；在非自耗电弧熔炼中制备CoCrFeNiV、CoCrFeNiMo、CoCrFeNiCu、CoCrFeNiTi、CoCrFeNiAl、CoCrFeNiNb、CoCrFeNiHf、CoCrFeNiTa、CoCrFeNiSi九种高熵合金铸锭；通过线切割得到制备扩散多元节所需块体；组装成扩散多元节在1050℃~1150℃进行168h-240h退火；
获取沉淀强化高熵合金成分的操作包括：
通过电子探针技术对扩散多元节中相接触的两种合金扩散退火后所产生的扩散层成分进行测试；
相接触的合金为CoCrFeNiD合金与CoCrFeNiE时，在CoCrFeNiD合金与CoCrFeNiE合金扩散所形成的扩散层中，以含量为纵坐标、以扩散距离作为横坐标，找到D、E含量的交汇点，并获取该扩散层中D元素和E元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分，其中D选自Al、V、Mo、Nb、Hf、Ta、Si、Cu和Ti中的一种元素；E选自Al、V、Mo、Nb、Hf、Ta、Si、Cu和Ti中的一种元素，且不与D相同。
本发明的方案和设计思想可以进行同类拓展。
拓展方法包括：
定义扩散多元节中相接触的两种合金为FG和FH；其中F的由至少2中元素组成；G和H为不同的元素，（优选为用量一致）；扩散退火后，以含量为纵坐标、以扩散距离作为横坐标；找到G、H含量的交汇点，并获取该扩散层中G元素和H元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分。
本发明基于扩散多元节技术的沉淀强化高熵合金成分设计方法，当面接触的合金为CoCrFeNiAl合金和CoCrFeNiTi合金时，在CoCrFeNiAl与CoCrFeNiTi扩散所形成的扩散层中，以含量为纵坐标、以扩散距离作为横坐标，找到Al、Ti含量的交汇点，并获取该扩散层中Al元素和Ti元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分Co x1Cr x2Fe x3Ni x4Al x5Ti x6，其中x1 、x2 、x3、 x4、 x5、 x6为相应元素的原子百分数；且23≤x1≤25、20≤x2≤22、24≤x3≤26、23≤x4≤25、2≤x5≤4、2≤x6≤4；
当相接触的合金为CoCrFeNiCu合金和CoCrFeNiTi合金时，在CoCrFeNiCu与CoCrFeNiTi扩散所形成的的扩散层中，以含量为纵坐标、以扩散距离作为横坐标，找到Cu、Ti含量的交汇点，并获取该扩散层中Cu元素和Ti元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分Co y1Cr y2Fe y3Ni y4Cu y5Ti y6，其中y1、y2、y3、y4、y5、y6为相应元素的原子百分数，且22≤y1≤24、18≤y2≤20、22≤y3≤24、24≤y4≤26、4≤y5≤6、4≤y6≤6。
本发明基于扩散多元节技术的沉淀强化高熵合金基体成分设计方法，原料的纯度不低于99.9%；块体为立方体或长方体，其各边的取值范围为就具体情况而定，优选为3-9mm。
作为本发明的一种方案；CoCrFeNiAl-CoCrFeNiTi扩散所得扩散层的成分从Co 24Cr 20Fe 23.4Ni 25.5Al 5.4Ti 1.7变化到Co 23Cr 22Fe 23.4Ni 21.6Al 0.4Ti 9.6；CoCrFeNiCu-CoCrFeNiTi扩散所得扩散层的成分从Co 22.4Cr 19.6Fe 23.5Ni 23Cu 10Ti 1.5变化到Co 22.2Cr 20.8Fe 22.7Ni 22.9Cu 0.8Ti 10.6。本发明选取曲线上Al和Ti、Cu和Ti具有相同数值的沉淀强化高熵合金成分点，化学式为Co 24Cr 20.9Fe 25.1Ni 24Al 3Ti 3和Co 22.8Cr 19Fe 23.5Ni 24.7Cu 5Ti 5。由于仪器测量存在误差，对于所测得成分曲线上的数值进行±1误差修正，故23≤x1≤25、20≤x2≤22、24≤x3≤26、23≤x4≤25、2≤x5≤4、2≤x6≤4，22≤y1≤24、18≤y2≤20、22≤y3≤24、24≤y4≤26、4≤y5≤6、4≤y6≤6。
本发明所述沉淀强化高熵合金的制备方法，按扩散多元节各扩散偶快速筛选得到不同的沉淀强化高熵合金基体成分，配取各原料；在非自耗电弧熔炼中制备，得到高熵合金铸锭；随后对铸锭进行均匀化处理、冷轧；最后对冷轧样品真空封管后进行固溶、时效处理。
本发明所述沉淀强化高熵合金的制备方法，当筛选获得的沉淀强化高熵合金成分的化学式为：Co x1Cr x2Fe x3Ni x4Al x5Ti x6或Co y1Cr y2Fe y3Ni y4Cu y5Ti y6，按所对应的化学式，配取Co、Cr、Fe、Ni、Al、Cu和Ti金属；在非自耗电弧熔炼中制备Co x1Cr x2Fe x3Ni x4Al x5Ti x6和Co y1Cr y2Fe y3Ni y4Cu y5Ti y6；随后对铸锭进行均匀化处理、冷轧；最后对冷轧样品真空封管后进行固溶、时效处理。
均匀化处理温度为1000-1200℃，时间为12h-24h；作为优选方案，均匀化温度为1100℃，保温时间为20h；
冷轧时，单道次变形量在5%-10%，总变形量在60%-80%；作为优选方案：单道次变形量为5%，总变形量为70%；
真空封管压强为0.3bar-0.5bar；
固溶处理温度为1000℃-1200℃，时间为4min-10min；
时效处理温度为600℃-900℃，时间为8h-50h。
本发明所述沉淀强化高熵合金的制备方法，所得Co x1Cr x2Fe x3Ni x4Al x5Ti x6和Co y1Cr y2Fe y3Ni y4Cu y5Ti y6均为FCC高熵合金；且面心立方基体上均匀分布的L1 2结构γˊ纳米析出粒子。
本发明相较于单相FCC高熵合金，产品的强度得到大幅度提高，同时还具有良好的塑性。
通过本发明的设计和制备方法，成功实现了高熵合金强度和塑性的同步提升。这不仅为高熵合金的设计提供了新的思路，而且为其产业化提供了必要条件。
 有益效果
第一，首次将扩散多元节技术成功运用于沉淀强化高熵合金成分设计，开拓了沉淀强化高熵合金设计的新方向，相较于其他设计方法，本发明可以进行成分的高通量筛选。同时，本发明能高效获得有用数据；基于有用数据的分析快速得到沉淀强化高熵合金的组成范围。本发明中，数据获取方式和数据分析方式均为首创。
       第二，基于扩散多元节技术进行沉淀强化高熵合金成分设计，具有流程短、节省材料和通用实效等特点。
       第三，经过适当的均匀化、冷轧、固溶和时效处理后，设计合金具有均匀细小的组织，同时在基体上析出大量均匀分布的纳米沉淀强化粒子，得到具有良好强度和塑性综合的沉淀强化高熵合金。
       综上所述，本发明基于扩散多元节快速筛选沉淀强化高熵合金基体合金技术，成功制备Co x1Cr x2Fe x3Ni x4Al x5Ti x6和Co y1Cr y2Fe y3Ni y4Cu y5Ti y6两种代表性的沉淀强化高熵合金，具有优异的强度和延展性综合。
此外，运用本发明的设计和制备方法，成功制备了一种代表性七元沉淀强化高熵合金Co 20Cr 16Fe 32.5Ni 17.5Al 4Cu 3Ti 7，表现出非常优异的强度和韧性组合（屈服强度1004 MPa，抗拉强度1508 MPa，延伸率26%）。
附图说明
图1为具体实施例1扩散多元节的结构设计图。其中A: CoCrFeNiV、B: CoCrFeNiMo、C: CoCrFeNiCu、D: CoCrFeNiTi、E: CoCrFeNiAl、F: CoCrFeNiNb、G:CoCrFeNiHf、H: CoCrFeNiTa、I: CoCrFeNiSi。
图2为扩散多元节中CoCrFeNiAl-CoCrFeNiTi扩散层区域组织形貌图。
图3为扩散多元节中CoCrFeNiCu-CoCrFeNiTi扩散层区域组织形貌图。
图4（a）为实施例1扩散多元节中Al和Ti扩散层部分成分浓度曲线;（b）为实施例1扩散多元节中Cu和Ti扩散层部分成分浓度曲线。
图5（a）（b）为实例2所制备的沉淀强化高熵合金（700℃/8h）在不同放大倍数下的显微组织SEM图，可以看到基体上均匀分布的纳米析出粒子。
图6为实例2所制备的沉淀强化高熵合金在不同时效温度后的拉伸工程应力应变曲线图。
图7（a）（b）为实例3所制备的沉淀强化高熵合金（700℃/8h）在不同放大倍数下的显微组织SEM图，有大量球状纳米析出粒子在基体上均匀分布。   
图8为实例3所制备的沉淀强化高熵合金在不同时效温度后的拉伸工程应力应变曲线图。
图9为扩散得到的CoCrFeNiAlCu-CoCrFeNiAlTi区域组织形貌图。
图10为实例4所制备的Co 20Cr 16Fe 32.5Ni 17.5Al 4Cu 3Ti 7沉淀强化高熵合金在固溶和不同时效温度处理后的拉伸工程应力应变曲线图。
本发明的实施方式
为了更加具体描述本发明实施的目的、技术方案和优点，以下结合实例对本发明进行进一步说明。以下所描述的实例是本发明一部分实例，以便将本发明公开范围更加完整传达给本领域的专业人员。
       以下实例中所用金属原料纯度不低于99.9%。
实施例1：扩散多元节制备
步骤一：通过砂纸和乙醇超声清洗去除原料上的氧化皮等杂质；分别按等原子比称量Co、Cr、Fe、Ni、X原料共8g；通过真空非自耗电弧熔炼制备成分为CoCrFeNiX（X 1=V、X 2=Mo、X 3=Cu、X 4=Ti、X 5=Al、X 6=Nb、X 7=Hf、X 8=Ta、X 9=Si）以FCC为基体的合金铸锭，每次熔炼时间1min，反复熔炼5次，冷却后取出；使用电火花线切割得到一定尺寸CoCrFeNiX块体铸锭，打磨清洗。
步骤二：制备镍包套和包套盖。将CoCrFeNiX合金块按图1的组装方式装配到包套中。利用真空电子束焊接将包套盖焊到包套上下两端。随后采用热等静压，使合金块紧密接触。其中真空电子束焊接焊深为1.5~2mm，热等静压参数为：980-1020℃、5-7h/130-170Mpa。将制备的扩散多元节在设定温度下进行扩散退火（1050-1150℃/10-20ds）。
步骤三：利用电子探针测试扩散偶中扩散层的成分。去除夹具同时打磨氧化皮；将扩散偶通过酚醛塑料粉镶嵌起来；通过机械抛光制备电子探针测试样品；通过电子探针对扩散层各元素成分进行测试。
根据测试结果绘制成分曲线：发现CoCrFeNiAl-CoCrFeNiTi扩散节形成了一百多微米的扩散层（如图2所示），扩散层中Co、Cr、Fe、Ni元素含量变化不大，只有Al和Ti有较大变化。CoCrFeNiCu-CoCrFeNiTi扩散节形成了一百多微米的扩散层（如图3所示），扩散层中Co、Cr、Fe、Ni元素含量变化不大，只有Cu和Ti有较大变化。
       实例2制备Co x1Cr x2Fe x3Ni x4Al x5Ti x6沉淀强化高熵合金            
步骤一：根据CoCrFeNiAl-CoCrFeNiTi扩散偶的成分曲线（如图4a所示），扩散层固溶体区成分从Co 24Cr 20Fe 23.4Ni 25.5Al 5.4Ti 1.7变化到Co 23Cr 22Fe 23.4Ni 21.6Al 0.4Ti 9.6，都可以作为Co x1Cr x2Fe x3Ni x4Al x5Ti x6沉淀强化高熵合金的候选成分。作为验证案例之一，这里选取曲线上Al和Ti具有相同数值的成分点，化学式为Co 24Cr 20.9Fe 25.1Ni 24Al 3Ti 3，其中x1 、x2 、x3、 x4、 x5、 x6为相应元素的原子百分数，由于仪器测量存在误差，对于所测得成分曲线上的数值进行±1误差修正，故23≤x1≤25、20≤x2≤22、24≤x3≤26、23≤x4≤25、2≤x5≤4、2≤x6≤4。
步骤二：按相应成分比例制备Co 24Cr 20.9Fe 25.1Ni 24Al 3Ti 3原料100g；在真空非自耗电弧熔炼炉中进行制备，每次熔炼时间1min，反复熔炼5次以上；在马弗炉中，铸锭在氩气氛围下于1100℃均匀化处理12个小时，然后水淬；将合金进行70%减薄率进行冷轧，每道次压下量为5%；后续在1100℃固溶6min，在600、700、800℃分别时效8h。
步骤三：通过扫描电镜对合金组织进行分析，发现有大量L1 2结构纳米级析出物均匀分布在基体上，图5所示。
步骤四：通过电火花切割狗骨试样，使用MTS实验机器进行拉伸实验，应变速率为1.4*10 -3s -1，在室温下进行；测试得到的拉伸工程应力应变曲线如图6所示，当时效温度为600℃，时效时间为8h时，屈服强度为759MPa，抗拉强度为1193MPa，延伸率为26%，晶粒尺寸为4.5μm；当时效温度为700℃，时效时间为8h时，屈服强度为851MPa，抗拉强度为1281MPa，延伸率为30%，晶粒尺寸为7.2μm；当时效温度为800℃，时效时间为8h时，屈服强度为685MPa，抗拉强度为1081MPa，延伸率为33%，晶粒尺寸为9.1μm。
实例3、基于扩散偶技术制备Co y1Cr y2Fe y3Ni y4Cu y5Ti y6沉淀强化高熵合金
       步骤一：根据CoCrFeNiCu-CoCrFeNiTi扩散偶的成分曲线（如图4b所示），扩散层固溶体区成分从Co 22.4Cr 19.6Fe 23.5Ni 23Cu 10Ti 1.5 变化到Co 22.2Cr 20.8Fe 22.7Ni 22.9Cu 0.8Ti 10.6，都可以作为Co y1Cr y2Fe y3Ni y4Cu y5Ti y6沉淀强化高熵合金的候选成分。作为验证案例之一，这里选取曲线上Cu和Ti具有相同数值的成分点，化学式为Co 22.8Cr 19Fe 23.5Ni 24.7Cu 5Ti 5，其中y1、y2、y3、y4、y5、y6为相应元素的原子百分数，由于仪器测量存在误差，对于所测得成分曲线上的数值进行±1误差修正，故22≤y1≤24、18≤y2≤20、22≤y3≤24、24≤y4≤26、4≤y5≤6、4≤y6≤6。
步骤二：按相应成分比例制备Co 22.8Cr 19Fe 23.5Ni 24.7Cu 5Ti 5原料100g；在真空非自耗电弧熔炼炉中进行制备，每次熔炼时间1min，反复熔炼5次以上；在马弗炉中，铸锭在氩气氛围下于1100℃均匀化处理12个小时，然后水淬；将合金进行70%减薄率进行冷轧，每道次压下量为5%；后续在1100℃固溶6min，在600、700、800℃分别时效8h。
步骤三：通过扫描电镜对合金组织进行分析，发现有大量L1 2结构纳米级析出物均匀分布在基体上，图7所示。
步骤四：通过电火花切割狗骨试样，使用MTS实验机器进行拉伸实验，应变速率为1.4*10 -3s -1，在室温下进行；测试得到的拉伸工程应力应变曲线如图8所示，当时效温度为600℃，时效时间为8h时，屈服强度为758MPa，抗拉强度为1072MPa，延伸率为18%，晶粒尺寸为6.6μm；当时效温度为700℃，时效时间为8h时，屈服强度为1020MPa，抗拉强度为1339MPa，延伸率为19%，晶粒尺寸为8.1μm；当时效温度为800℃，时效时间为8h时，屈服强度为738MPa，抗拉强度为1160MPa，延伸率为21%，晶粒尺寸为10.2μm。
实例4、基于扩散偶技术制备Co y1Cr y2Fe y3Ni y4Al y5Cu y6Ti y7沉淀强化高熵合金
步骤一：根据测试结果，发现CoCrFeNiAlCu-CoCrFeNiAlTi扩散区域形成了一百多微米的扩散层（如图9a所示）。根据CoCrFeNiAlCu-CoCrFeNiAlTi扩散区的成分曲线（如图9b所示），扩散层固溶体区成分从Co 19.5Cr 17.1Fe 33.8Ni 17.1Al 3.6Cu 1.5Ti 7.4连续变化到Co 19.5Cr 15.7Fe 30.9Ni 17.8Al 4.4Cu 5.1Ti 6.7，都可以作为Co y1Cr y2Fe y3Ni y4Al y5Cu y6Ti y7沉淀强化高熵合金的候选成分。作为验证案例之一，这里选取曲线上成分点Co 20Cr 16Fe 32.5Ni 17.5Al 4Cu 3Ti 7，其中y1、y2、y3、y4、y5、y6、y7为相应元素的原子百分数，由于仪器测量存在误差，对于所测得成分曲线上的数值进行±1误差修正，故19≤y1≤20、15.5≤y2≤17.5、30≤y3≤34、17≤y3≤18、3≤y4≤5、1.5≤y5≤5.5、6≤y6≤8。
步骤二：按相应成分比例制备Co 20Cr 16Fe 32.5Ni 17.5Al 4Cu 3Ti 7原料100g；在真空非自耗电弧熔炼炉中进行制备，每次熔炼时间1min，反复熔炼5次以上；在马弗炉中，铸锭在氩气氛围下于1100℃均匀化处理12个小时，然后水淬；将合金进行70%减薄率进行冷轧，每道次压下量为5%；后续在1100℃固溶6min，在600、700、800℃分别时效8h。
步骤三：通过电火花切割狗骨试样，使用MTS实验机器进行拉伸实验，应变速率为1.4*10 -3s -1，在室温下进行；测试得到的拉伸工程应力应变曲线如图8所示，当时效温度为600℃，时效时间为8h时，屈服强度为1030MPa，抗拉强度为1412MPa，延伸率为27%；当时效温度为700℃，时效时间为8h时，屈服强度为1004MPa，抗拉强度为1508MPa，延伸率为26%；当时效温度为800℃，时效时间为8h时，屈服强度为659MPa，抗拉强度为1195MPa，延伸率为24%。
 
       实例结果总结：
       本发明基于扩散多元节技术，利用不同CoCrFeNiX-CoCrFeNiY、CoCrFeNiXY-CoCrFeNiXZ合金组的扩散信息，实现了沉淀强化高熵合金固溶体的成分区间的快速筛选。作为该方法可靠性的验证和应用案例，通过选取扩散筛选出的候选区间某一成分，通过后续适当机械热处理，得到均匀分布在基体上的纳米级强化相，成功开发两种新型高性能Co x1Cr x2Fe x3Ni x4Al x5Ti x6、Co y1Cr y2Fe y3Ni y4Cu y5Ti y6和Co y1Cr y2Fe y3Ni y4Al y5Cu y6Ti y7沉淀强化高熵合金产品。该技术拓展到了沉淀强化高熵合金的优化设计领域，其相比于其他高熵合金，本发明制备的高熵合金同时具有良好的强度和延展性综合，极大促进沉淀强化高熵合金设计，具有很大的科研潜力和实用价值。
显然，上述实施例仅仅是为清楚地说明本发明的方案所作的举例，而并非对本发明实施方式的限定。对于所属领域的普通技术人员来说,在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (7)

  1. 基于扩散多元节技术的沉淀强化高熵合金成分设计方法，其特征在于，包括下述步骤：
    步骤A制备扩散多元节并进行退火
    制备至少N种合金块体，所述合金为高熵合金或中熵合金块体；将所制备的N种合金块体中至少2种，按扩散多元节的要求放置在一起，组装成扩散多元节，然后在1050℃~1150℃进行168h-240h退火；得到单相固溶体扩散层；扩散偶中相接触的两种合金中，一种合金的组成元素的种类数为S 1、另外一种合金的组成元素的种类数为S 2，0≤|S 1-S 2|≤2；所述N为大于等于2的正整数；
    扩散偶中相接触的两种合金中，至少有两种元素的种类和用量一致；
    定义相接触的两种合金块体分别为A、B；A、B中种类不相同的元素定义为A1、A2、…、An；B1、B2、…、Bp，所述n为小于等于2的正整数；所述p为小于等于2的正整数；
    步骤A中，所述高熵合金由Co、Cr、Fe、Ni、Al、Cu、Hf、Zr、Nb、Ta、W、Mo、V、Si、稀土元素和Ti中至少四种元素构成；
    步骤A中，所述中熵合金由Co、Cr、Fe、Ni、Al、Cu、Hf、Zr、Nb、Ta、W、Mo、V、Si、稀土元素和Ti中至少三种元素构成；
    所述稀土元素选自Gd、Tb、Dy、Ho、Er、Sc中的中至少一种；
    步骤B、获取沉淀强化高熵合金成分范围
    通过电子探针技术对步骤A中退火实验后所得每一组扩散偶所对应的扩散层成分进行测试；基于测试结果，得出该扩散层中各元素的含量范围，在测结果中找到Ai元素和Bj元素的交叉点；并获取扩散层中Ai元素和Bj元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正；得到沉淀强化高熵合金成分范围；所述Ai选自A1、A2、…、An中的一种元素；所述Bj选自B1、B2、…、Bp中的一种元素；
    定义扩散多元节中相接触的两种合金为FG和FH；其中F的由至少2中元素组成；G和H为不同的元素；扩散退火后，以含量为纵坐标、以扩散距离作为横坐标；找到G、H含量的交汇点，并获取该扩散层中G元素和H元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分。
  2. 根据权利要求1所述的基于扩散多元节技术的沉淀强化高熵合金成分设计方法，其特征在于：扩散多元节中相接触的两种合金中，至少有3种元素在二种合金中均用到，且对应元素在不同合金中的摩尔含量相等。
  3. 根据权利要求1所述的基于扩散多元节技术的沉淀强化高熵合金成分设计方法，其特征在于：
    制备所需扩散多元节并进行退火包括：
    以Co、Cr、Fe、Ni、Al、V、Mo、Nb、Hf、Ta、Si、Cu和Ti金属作为原料，在非自耗电弧熔炼中制备CoCrFeNiV、CoCrFeNiMo、CoCrFeNiCu、CoCrFeNiTi、CoCrFeNiAl、CoCrFeNiNb、CoCrFeNiHf、CoCrFeNiTa、CoCrFeNiSi九种高熵合金铸锭；通过线切割得到制备扩散多元节所需块体；
    原料的纯度不低于99.9%；
    获取沉淀强化高熵合金成分的操作包括：
    通过电子探针技术对扩散多元节中相接触的两种合金扩散退火后所产生的扩散层成分进行测试；
    相接触的合金为：CoCrFeNiD合金与CoCrFeNiE，在CoCrFeNiD合金与CoCrFeNiE合金扩散所形成的扩散层中，以含量为纵坐标、以扩散距离作为横坐标；找到D、E含量的交汇点，并获取该扩散层中D元素和E元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分，其中D选自Al、V、Mo、Nb、Hf、Ta、Si、Cu和Ti中的一种元素；E选自Al、V、Mo、Nb、Hf、Ta、Si、Cu和Ti中的一种元素，且不与D相同。
  4. 根据权利要求1所述的基于扩散多元节技术的沉淀强化高熵合金成分设
    计方法，其特征在于：
    当相接触的合金为CoCrFeNiAl合金和CoCrFeNiTi合金时，
    在CoCrFeNiAl与CoCrFeNiTi扩散所形成的扩散层中，以含量为纵坐标、以扩散距离作为横坐标；找到Al、Ti含量的交汇点，并获取该扩散层中Al元素和Ti元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分Co x1Cr x2Fe x3Ni x4Al x5Ti x6，其中x1 、x2 、x3、 x4、 x5、 x6为相应元素的原子百分数；且23≤x1≤25、20≤x2≤22、24≤x3≤26、23≤x4≤25、2≤x5≤4、2≤x6≤4；
    当相接触的合金为CoCrFeNiCu合金和CoCrFeNiTi合金时，
    在CoCrFeNiCu与CoCrFeNiTi扩散所形成的的扩散层中，以含量为纵坐标、以扩散距离作为横坐标；找到Cu、Ti含量的交汇点，并获取该扩散层中Cu元素和Ti元素的交叉点所对应的其他元素的含量；然后在各元素含量的基础上进行±1的误差修正，得到沉淀强化高熵合金成分Co y1Cr y2Fe y3Ni y4Cu y5Ti y6，其中y1、y2、y3、y4、y5、y6为相应元素的原子百分数，且22≤y1≤24、18≤y2≤20、22≤y3≤24、24≤y4≤26、4≤y5≤6、4≤y6≤6。
  5. 根据权利要求1-4任意一项所述沉淀强化高熵合金的制备方法，其特征
    在于：
    按设计得到不同的沉淀强化高熵合金成分，配取各原料；在非自耗电弧熔炼中制备，得到高熵合金铸锭；随后对铸锭进行均匀化处理、冷轧；最后对冷轧样品真空封管后进行固溶、时效处理。
  6. 根据权利要求5所述沉淀强化高熵合金的制备方法，其特征在于：
    当筛选获得的沉淀强化高熵合金成分的化学式为：
    Co x1Cr x2Fe x3Ni x4Al x5Ti x6或Co y1Cr y2Fe y3Ni y4Cu y5Ti y6，
    按所对应的化学式，配取Co、Cr、Fe、Ni、Al、Cu和Ti金属；在非自耗电弧熔炼中制备Co x1Cr x2Fe x3Ni x4Al x5Ti x6和Co y1Cr y2Fe y3Ni y4Cu y5Ti y6；随后对铸锭进行均匀化处理、冷轧；最后对冷轧样品真空封管后进行固溶、时效处理；
    均匀化处理温度为1000-1200℃，时间为12h-24h；
    冷轧时，单道次变形量在5%-10%，总变形量在60%-80%；
    真空封管压强为0.3bar-0.5bar；
    固溶处理温度为1000℃-1200℃，时间为4min-10min；
    时效处理温度为600℃-900℃，时间为8h-50h。
  7. 根据权利要求6所述沉淀强化高熵合金的制备方法；其特征在于：所得Co x1Cr x2Fe x3Ni x4Al x5Ti x6和Co y1Cr y2Fe y3Ni y4Cu y5Ti y6均为FCC高熵合金；且面心立方基体上均匀分布的L1 2结构γˊ纳米析出粒子。
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