A wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structures

Abstract

This invention relates to a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structures. This high-entropy alloy is a single-phase high-entropy alloy, and its schematic chemical composition formula is H. 95~85 P 3~13 B2, the proportions of each element are expressed as atomic percentages; where H represents a chemically complex solid solution with non-equiatomic ratios, specifically (Co... 25 Ni 23 Cr 20 Fe 20 ), (Cr 29 Fe 27 Ni 32 Nb6) or (Co 39 Ni 35 Nb 14 P represents any one of the following: (MoW), (TiV), or (TiAl); B represents boron, a grain boundary stabilizing element. This invention features a simple processing route, high preparation efficiency, low raw material cost, and produces high-entropy alloys with excellent comprehensive properties. It has significant application prospects in the wear resistance and load-bearing capacity of moving / transmission components in advanced mechanical systems in the automotive, energy, and aerospace fields.

Description

Technical Field

[0001] This invention relates to the field of high-performance high-temperature wear-resistant alloy material preparation technology, and in particular to a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure. Background Technology

[0002] In modern industry, especially in aerospace, energy, and defense, mechanical components often operate in high-temperature environments. Wear of metallic materials under high-temperature conditions has become a key factor limiting their service life and performance. In existing technologies, wear on the surface of metallic materials mainly stems from thermal softening and tribo-oxidation, leading to the formation of brittle oxide fragments that are prone to cracking and peeling, thus exacerbating wear. Although some oxide glazes can improve sliding friction under certain conditions through hardening and lubrication, under high contact stress, the glaze often exhibits peeling and adhesive wear, limiting its wear resistance (Rasearch 2023;6:0160). To address this issue, existing technologies typically employ solid lubricants (such as layered two-dimensional materials, metal fluorides, and metal inorganic acid salts) to improve the triboelectric properties of materials at high temperatures (Tribology International 2019;133:206-223). However, solid lubricants exhibit metallurgical incompatibility with the metal matrix, easily leading to a reduction in the mechanical properties of the alloy. Furthermore, solid lubricants lack stability under high temperature and high load conditions, and lubrication failure accelerates glaze detachment and wear. Therefore, improving the wear resistance of materials through adaptive control of their microstructure under high temperature conditions remains a pressing technical challenge.

[0003] In recent years, high-entropy alloys (also known as multi-principal element alloys or chemically complex alloys) have gradually become a new type of material for breaking through the performance bottlenecks of traditional alloys due to their unique high-entropy effect and multi-principal element design (Science 2024;384:1017-1022; Nature 2022;602:251-257). High-entropy alloys tend to form complex solid solution structures rather than traditional intermetallic compounds, thus exhibiting good strength-toughness matching, thermal stability, and wear resistance. By controlling the intrinsic or additional heterostructures in high-entropy alloy systems, the problems of strength-ductility trade-off and wear resistance degradation in traditional metallic materials at high temperatures can be effectively solved. Currently, heterostructures at various scales have been developed in high-entropy alloy systems, including: (i) local atomic-level chemical order; (ii) indistinguishable nanoclusters or composites embedded in the matrix; (iii) precipitates, layered eutectic phases, and martensite induced by compositional segregation; (iv) lattice defects such as twins, stacking faults, and grain boundaries; and (v) gradient grain size distributions from nanoscale to microscale (Nature Communications 2019;10:5623). Among these, heteroprecipitates are a particularly effective strengthening mechanism. By introducing compositional fluctuations and establishing secondary phase interfaces in a multi-component solid solution matrix, they can not only regulate the nucleation and propagation of dislocations during deformation but also influence the tribochemical reactions that occur during wear (Journal of Materials Science & Technology 2023;153:75-91).

[0004] However, designing and introducing ideal wear-resistant heterostructures into existing high-entropy alloy systems still faces several challenges. First, according to the Hertzian contact model, frictional contact stress decreases with depth, resulting in a large strain gradient. This strain gradient may amplify the local shear instability of the heterostructure during deformation and increase wear. Second, existing methods for inducing precipitates and heterostructures (such as complex heat treatment processes and surface mechanical polishing) have significant limitations in terms of microstructure control and friction load bearing capacity, making it difficult to simultaneously achieve a coordinated development of strength, toughness, and wear resistance. Furthermore, based on the physicochemical properties of multi-principal-element solid solution matrices, simultaneously introducing heterogeneous phase precipitation and bimodal grain distribution is extremely difficult. On the one hand, heterogeneous phase precipitation often consumes second-phase nucleating elements in the alloy system, inhibiting widespread dynamic recrystallization in the initial grains; on the other hand, bimodal grain size distribution may lead to uneven precipitation of the precipitate phase, thus significantly reducing the overall performance of the material.

[0005] In summary, it is of great significance to develop low-cost and high-processing-efficiency design strategies to simultaneously introduce heterogeneous grains and phase structures in high-entropy alloy systems that are sufficient to resist extreme wear conditions (wide temperature range and GPa-level Hertzian contact stress). Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure that is low in cost and reliable in performance.

[0007] To address the aforementioned problems, the present invention provides a wear-resistant high-entropy alloy possessing both heterogeneous grain and heterogeneous phase structures, characterized in that: the high-entropy alloy is a single-phase high-entropy alloy, and its schematic chemical composition formula is H. 95~85 P 3~13 B2, the proportions of each element are expressed as atomic percentages; where H represents a non-equiatomic chemically complex solid solution, which is (Co 25 Ni 23 Cr 20 Fe 20 ), (Cr 29 Fe 27 Ni 32 Nb6) or (Co 39 Ni 35 Nb 14 P represents any one of the following: (MoW), (TiV), or (TiAl); B represents the grain boundary stabilizing element boron.

[0008] The preparation method of the wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described above includes the following steps:

[0009] (1) Co powder, Ni powder, Cr powder, Fe powder, Nb powder, Ti powder, Al powder, V powder, Mo powder, W powder and B powder are weighed according to a preset atomic ratio and put into a planetary high-energy ball mill. Dry grinding and alloying treatment is carried out under atmospheric conditions to obtain dry supersaturated high-entropy solid solution powder.

[0010] (2) Add 5% by mass of ethyl acetate as a process control agent to the dry supersaturated high-entropy solid solution powder, and put it into a planetary ball mill again for wet grinding and crystallization under the protection gas of argon to obtain a moist ultrafine crystalline powder precursor.

[0011] (3) The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm.

[0012] (4) The pre-alloyed high-entropy solid solution powder is sintered by spark plasma to obtain a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure.

[0013] In step (1), the Co powder, Ni powder, Cr powder, Fe powder, Nb powder, Ti powder, Al powder, V powder, Mo powder, and W powder are all spherical or irregular in shape, with a particle size of 10~35 μm and a purity of >99.9%.

[0014] In step (1), the particle size of powder B is 500 nm and the purity is >99.9%.

[0015] The conditions for dry grinding alloying treatment in step (1) are as follows: using cemented carbide balls with a diameter of 5-15 mm as grinding balls, a ball-to-material ratio of 4-6:1, a rotation speed of 150-250 r / min, and a running time of 15-45 h.

[0016] The conditions for wet grinding and crystallization in step (2) are as follows: using cemented carbide balls with a diameter of 5-15 mm as grinding balls, a ball-to-material ratio of 1.5-2.5:1, a rotation speed of 100-200 r / min, and a running time of 3-8 h.

[0017] The conditions for spark plasma sintering in step (4) are: vacuum degree below 1 Pa, sintering temperature 1100~1250 ℃, applied pressure 30~40 MPa, and holding time 8~15 min.

[0018] The heating process in step (4) of the spark plasma sintering process refers to a heating rate of 40~60 ℃ / min from room temperature to 700 ℃, and a heating rate of 80~100 ℃ / min from 700 ℃ to 1100~1250 ℃.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Based on the design concept of high strength and toughness matching and wear-resistant heterogeneous structure, this invention introduces heterogeneous phase precipitation and dynamic bimodal grain size distribution simultaneously into a multi-principal chemical complex solid solution through an oxygen-containing mechanical alloying process combined with spark plasma sintering technology, thereby obtaining a high-performance heterogeneous high-entropy alloy:

[0021] (1) By controlling the element ratio in (CoNiCrFe), (CrFeNiNb), or (CoNiNb), a chemically complex matrix with high mixing entropy and near-zero mixing enthalpy is prepared to ensure that the alloy matrix has high-temperature stability and high solubility limit.

[0022] (2) The formation of heterogeneous interfaces and compositional fluctuations is driven by the induction of second-phase precipitation and continuous dynamic recrystallization of multi-principal solid solutions during solid-phase diffusion by second-phase auxiliary nucleating agents (MoW), (TiV) or (TiAl).

[0023] (3) Stabilize grain boundaries by doping with boron, while reducing residual stress at heterogeneous grain interfaces;

[0024] (4) By utilizing the Joule heat-driven thermal diffusion during oxygen alloying and spark plasma sintering, the supersaturated solid solution can simultaneously maintain a metastable composite solid solution state with dual heterogeneous precipitation and bimodal grain size distribution.

[0025] 2. The wear-resistant high-entropy alloy of the present invention, which combines heterogeneous grains and heterogeneous phases, has a multi-principal solid solution structure strengthened by dual heterogeneous precipitation. The grains are composed of hierarchical grain regions with grain sizes greater than and less than 1 micrometer (initial grains and dynamic recrystallization regions). The constituent elements undergo extensive compositional fluctuations with the spatial distribution of the heterogeneous structure. There are no sintering structural defects such as microcracks and pores inside the material.

[0026] 3. Testing revealed that the wear-resistant high-entropy alloy of this invention, possessing both heterogeneous grain and heterogeneous phase structures, exhibits a compressive yield strength of no less than 1.4 GPa, an ultimate compressive strength of no less than 1.9 GPa, and a plastic strain of no less than 12% at room temperature; at 600 °C, its compressive yield strength is no less than 1.0 GPa, its ultimate compressive strength is no less than 1.3 GPa, and its plastic strain is no less than 20%. Furthermore, it demonstrates excellent wear resistance over a wide temperature range, with a wear rate consistently maintained at 10% over a wide temperature range from room temperature to 1000 °C. - 5 mm 3 Within the order of Nm.

[0027] 4. The present invention has a simple preparation process, low raw material cost, and high performance reliability, and has important application prospects in the wear resistance and load-bearing of motion / transmission components of advanced mechanical systems in the fields of automobiles, energy and aerospace. Attached Figure Description

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] Figure 1 The Co sintered by spark plasma sintering in Example 1 of this invention 25 Ni 23 Cr 20 Fe 20 XRD diffraction pattern of Ti6Al4B2 high-entropy alloy (left) and corresponding 3D micro-CT image (right).

[0030] Figure 2 Co prepared in Example 1 of this invention 25 Ni 23 Cr 20 Fe 20 TEM image (a) and corresponding EDS composition distribution (b) of Ti6Al4B2 high-entropy alloy.

[0031] Figure 3Co prepared in Example 1 of this invention 25 Ni 23 Cr 20 Fe 20 Compression stress-strain curves of Ti6Al4B2 from room temperature to high temperature.

[0032] Figure 4 Co prepared in Example 1 of this invention 25 Ni 23 Cr 20 Fe 20 Wear rate of Ti6Al4B2 high-entropy alloy at test temperatures of room temperature, 400 °C, 600 °C, 800 °C and 1000 °C.

[0033] Figure 5 The original powder in Example 2 of this invention, the pre-alloyed powder prepared by oxygen-containing high-energy ball milling, and the Cr prepared by spark plasma sintering. 29 Fe 27 Ni 32 XRD pattern of Nb6Ti2V2B2 high-entropy alloy, and (b) EBSD grain orientation distribution of sintered bulk sample. Detailed Implementation

[0034] A wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure, wherein the high-entropy alloy is a single-phase high-entropy alloy, and its schematic chemical composition formula is H. 95~85 P 3~13 B2, the proportions of each element are expressed as atomic percentages; where H represents a chemically complex solid solution with non-equiatomic ratios, specifically (Co... 25 Ni 23 Cr 20 Fe 20 ), (Cr 29 Fe 27 Ni 32 Nb6) or (Co 39 Ni 35 Nb 14 P represents any one of the following: (MoW), (TiV), or (TiAl); B represents the grain boundary stabilizing element boron.

[0035] Its preparation method includes the following steps:

[0036] (1) Co powder, Ni powder, Cr powder, Fe powder, Nb powder, Ti powder, Al powder, V powder, Mo powder, W powder and B powder are weighed according to a preset atomic ratio and put into a planetary high-energy ball mill. Under atmospheric conditions, hard alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 4~6:1, and the rotation speed is 150~250 r / min for dry grinding alloying treatment. The process is run for 15~45 h to obtain dry supersaturated high entropy solid solution powder.

[0037] Among them, Co powder, Ni powder, Cr powder, Fe powder, Nb powder, Ti powder, Al powder, V powder, Mo powder and W powder are all spherical or irregular in shape, with a particle size of 10~35 μm and a purity of >99.9%.

[0038] The particle size of powder B is 500 nm, and the purity is >99.9%.

[0039] (2) Add 5% by mass of ethyl acetate as a process control agent to the dry supersaturated high entropy solid solution powder, and put it back into a planetary ball mill. Under the protection of argon gas, use cemented carbide balls with a diameter of 5~15 mm as grinding balls, the ball-to-material ratio (g / g) is 1.5~2.5:1, and the rotation speed is 100~200 r / min for wet grinding and crystallization. Run for 3~8 h to obtain a moist ultrafine crystalline powder precursor.

[0040] (3) The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm.

[0041] (4) The pre-alloyed high-entropy solid solution powder is sintered by spark plasma to obtain a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure.

[0042] The conditions for spark plasma sintering are as follows: vacuum level below 1 Pa, sintering temperature 1100~1250 ℃, applied pressure 30~40 MPa, and holding time 8~15 min. The heating process refers to a heating rate of 40~60 ℃ / min from room temperature to 700 ℃, and a heating rate of 80~100 ℃ / min from 700 ℃ to 1100~1250 ℃.

[0043] Example 1 Preparation of Co 25 Ni 23 Cr 20 Fe 20 Ti6Al4B2 high-entropy alloy:

[0044] (1) Dry grinding alloying process: Co powder, Ni powder, Cr powder, Fe powder, Ti powder, Al powder and B powder are mixed according to the ratio shown in Table 1, weighed using an electronic balance and placed in a planetary ball mill. Tungsten carbide alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 4:1, the rotation speed is 200 r / min, and dry grinding alloying is carried out under atmospheric conditions for 32 h to obtain dry supersaturated high entropy solid solution powder.

[0045] Table 1: Alloy raw material ratio (wt.%)

[0046]

[0047] (2) Wet grinding and crystallization process: 5% of ethyl acetate by mass is added to the dry supersaturated high entropy solid solution powder as a process control agent, and the powder is placed in a planetary ball mill again. Hard alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 1.5:1, the rotation speed is 100 r / min, and the mill runs for 3 h under the protection of argon gas to obtain a moist ultrafine crystalline powder precursor.

[0048] (3) Drying: The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm.

[0049] (4) The pre-alloyed high-entropy solid solution powder is placed in a graphite mold (φ30 mm or φ52 mm) lined with graphite paper, and then placed in a spark plasma sintering furnace. Sintering begins at a preset constant pressure of 35 MPa. Sintering parameters: vacuum degree below 1 Pa, sintering temperature 1200 ℃, holding time 8 min, heating rate from room temperature to 700 ℃ at 50 ℃ / min, and heating rate from 700 ℃ to 1200 ℃ at 90 ℃ / min. After sintering, the furnace is cooled to room temperature to obtain Co with both wear-resistant heterogeneous grains and phase structure. 25 Ni 23 Cr 20 Fe 20 Ti6Al4B2 high-entropy alloy.

[0050] The obtained sintered bulk samples were characterized by XRD diffraction and 3D microscopic CT, such as... Figure 1The results show that after spark plasma sintering, heterogeneous second phases of Cr2B and Al2O3 types precipitated in the multi-principal FCC matrix, proving that compositional segregation occurred during the dispersion process. Simultaneously, the results indicate that the nano-precipitates (red area) are uniformly distributed throughout the sample, with a volume fraction as high as 42%, and no defects were observed. Furthermore, the high XRD diffraction peak intensity of the bulk alloy sample indicates that the sample prepared in this invention has high purity and crystallinity.

[0051] The resulting sintered bulk material was processed into TEM test sections using FIB technology and then characterized by TEM. Figure 2 The results show that the sample exhibits a heterogeneous bimodal grain size distribution. (Magnified BF-TEM image) Figure 2 a) High-density nanoprecipitates embedded in gradient grains, ranging in size from tens to hundreds of nanometers, are shown. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) mapping ( Figure 2 (b) indicates that the heterogeneous structure comprises (Ti, O)-rich nanoprecipitates (approximately 39 vol%), and phases rich in (Cr, O) (<2 vol%) and (Al, O) (approximately 5 vol%), wherein oxygen is incorporated during mechanical alloying. Combined XRD and TEM analyses demonstrate that this invention successfully prepared a wear-resistant high-entropy alloy possessing both heterogeneous grain and heterogeneous phase structures.

[0052] The obtained bulk single-phase high-entropy alloy was machined into cylindrical compression samples with a diameter of φ3×6 mm and polished using 2000-grit metallographic sandpaper. A WDW-200 material mechanical testing machine was used at a speed of 5 × 10⁻⁶ mm. -4 s -1 The strain rate test assesses the compressibility of the sample from room temperature to 1000 °C, and the test is repeated at least three times. Figure 3 As shown, at room temperature, this high-entropy alloy exhibits a yield strength of 1.8 GPa, an ultimate compressive strength of 2.3 GPa, and a fracture strain of 13%. At 600 °C, the yield strength remains at 1.4 GPa, the ultimate compressive strength is 1.6 GPa, while the fracture strain increases to 20%. With further increases in temperature, the yield strength decreases to 408 MPa at 800 °C and to 105 MPa at 1000 °C, and above 800 °C, the fracture strain exceeds 40%. This demonstrates the Co prepared in this invention. 25 Ni 23 Cr 20 Fe 20 The Ti6Al4B2 high-entropy alloy exhibits excellent strength-toughness matching over a wide temperature range.

[0053] The obtained bulk single-phase high-entropy alloy was machined into cylindrical samples with a diameter of φ15 × 3 mm and polished with metallographic sandpaper to achieve a surface roughness of 20 nm. Its wear performance was tested using an HT-1000 ball-and-disc commercial high-temperature friction tester. The test pair consisted of Si3N4 ceramic balls (hardness approximately 15 GPa), the test distance was 360 m, the Hertzian contact stress was approximately 1.2 GPa, and the sliding speed was 0.2 m / s. The test temperatures were set to room temperature, 400 ℃, 600 ℃, 800 ℃, and 1000 ℃. After the test, the wear rate of the sample was measured using a MicroXAM-800 non-contact three-dimensional profilometer, where the wear rate was measured as the ratio between the wear volume and the product of the sliding distance and the applied load. Figure 4 As shown, the wear rate of this single-phase high-entropy alloy remained stable at (0.2~3.5) × 10⁻⁶ from room temperature to 1000 °C. -5 mm 3 The order of magnitude is / Nm. Experimental results show that Co 25 Ni 23 Cr 20 Fe 20 Ti6Al4B2 high-entropy alloy exhibits excellent wear resistance over a wide temperature range.

[0054] Example 2 Preparation of Cr 29 Fe 27 Ni 32 Nb6Ti2V2B2 high-entropy alloy:

[0055] (1) Dry grinding alloying process: Cr powder, Fe powder, Ni powder, Nb powder, Ti powder, V powder and B powder are mixed according to the ratio shown in Table 2, weighed using an electronic balance and placed in a planetary ball mill. Tungsten carbide alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 5:1, the rotation speed is 150 r / min, and dry grinding alloying is carried out under atmospheric conditions for 45 h to obtain dry supersaturated high entropy solid solution powder.

[0056] Table 2: Alloy raw material ratio (wt.%)

[0057]

[0058] (2) Wet grinding and crystallization process: Add 5% by mass of ethyl acetate as a process control agent to the dry supersaturated high entropy solid solution powder, and put it into a planetary ball mill again. Use cemented carbide balls with a diameter of 5~15 mm as grinding balls, the ball-to-material ratio (g / g) is 2:1, the rotation speed is 150 r / min, and run for 6 h under the protective gas of argon to obtain a moist ultrafine crystalline powder precursor.

[0059] (3) Drying: The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm.

[0060] The obtained initial raw material powder and pre-alloyed high-entropy solid solution powder were characterized by XRD, such as... Figure 5 As shown in (a), distinct peaks corresponding to all elements can be observed in the raw material powder sample. After high-energy ball milling, the intensity of most diffraction characteristic peaks weakens, and the peaks of some alloying elements (Ti, V) disappear, indicating that mutual dissolution occurred between the constituent elements. In contrast, the peaks of Cr, Fe, and Ni are more pronounced. This indicates that the alloying elements partially dissolve in the matrix, forming a supersaturated multi-component solid solution. Furthermore, due to local lattice distortion, the full width at half maximum (FWHM) of the diffraction peaks increases with the extension of ball milling time. The alloyed powders are all composed of FCC and several BCC solid solutions.

[0061] (4) The pre-alloyed high-entropy solid solution powder is placed in a graphite mold (φ30 mm or φ52 mm) lined with graphite paper, and then placed in a spark plasma sintering furnace. Sintering begins at a preset constant pressure of 30 MPa. Sintering parameters: vacuum degree below 1 Pa, sintering temperature 1100 ℃, holding time 12 min, heating rate from room temperature to 700 ℃ at 60 ℃ / min, and heating rate from 700 ℃ to 1100 ℃ at 80 ℃ / min. After sintering, the furnace is cooled to room temperature to obtain Cr with both wear-resistant heterogeneous grains and phase structure. 29 Fe 27 Ni 32 Nb6Ti2V2B2 high-entropy alloy.

[0062] The obtained sintered bulk samples were characterized by XRD diffraction, such as... Figure 5 (a) shows that the crystallinity of the sample improved after sintering. The high-entropy alloy comprises a main matrix phase and two heterogeneous phases. The matrix phase is a (Fe, Ni) type FCC solid solution, while the heterogeneous phases include boride and oxide phases with NiB and Ni2Ti4O structures. Combined with XRD and EBSD analysis, this invention successfully prepared a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structures.

[0063] Example 3 Preparation of Cr 29 Fe 27 Ni 32 Nb6Mo2W2B2 high-entropy alloy:

[0064] (1) Dry grinding alloying process: Cr powder, Fe powder, Ni powder, Nb powder, Mo powder, W powder and B powder are mixed according to the ratio shown in Table 3, weighed using an electronic balance and placed in a planetary ball mill. Tungsten carbide alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 6:1, the rotation speed is 250 r / min, and dry grinding alloying is carried out under atmospheric conditions for 20 h to obtain dry supersaturated high entropy solid solution powder.

[0065] Table 3: Alloy Raw Material Proportions (wt.%)

[0066]

[0067] (2) Wet grinding and crystallization process: 5% of ethyl acetate by mass is added to the dry supersaturated high entropy solid solution powder as a process control agent, and the powder is placed in a planetary ball mill again. Hard alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 2.5:1, the rotation speed is 200 r / min, and the mill runs for 8 h under the protection of argon gas to obtain a moist ultrafine crystalline powder precursor.

[0068] (3) Drying: The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm.

[0069] (4) The pre-alloyed high-entropy solid solution powder was placed in a graphite mold (φ30 mm or φ52 mm) lined with graphite paper, and then placed in a spark plasma sintering furnace. Sintering was initiated at a preset constant pressure of 40 MPa. Sintering parameters: vacuum degree below 1 Pa, sintering temperature 1250 ℃, holding time 15 min, heating rate from room temperature to 700 ℃ 40 ℃ / min, and heating rate from 700 ℃ to 1250 ℃ 100 ℃ / min. After sintering, the furnace was cooled to room temperature to obtain Cr with both wear-resistant heterogeneous grains and phase structure. 29 Fe 27 Ni 32 Nb6Mo2W2B2 high-entropy alloy.

[0070] Example 4 Preparation of Co 39 Ni 35 Nb 14 Ti6Al4B2 high-entropy alloy:

[0071] (1) Dry grinding alloying process: Co powder, Ni powder, Nb powder, Ti powder, Al powder and B powder are mixed according to the ratio shown in Table 4, weighed using an electronic balance and placed in a planetary ball mill. Tungsten carbide alloy balls with a diameter of 5~15 mm are used as grinding balls, the ball-to-material ratio (g / g) is 4.5:1, the rotation speed is 250 r / min, and dry grinding alloying is carried out under atmospheric conditions for 15 h to obtain dry supersaturated high entropy solid solution powder.

[0072] Table 4: Alloy Raw Material Proportions (wt.%)

[0073]

[0074] (2) Wet grinding and crystallization process: Add 5% by mass of ethyl acetate as a process control agent to the dry supersaturated high entropy solid solution powder, and put it into a planetary ball mill again. Use cemented carbide balls with a diameter of 5~15 mm as grinding balls, the ball-to-material ratio (g / g) is 2:1, the rotation speed is 150 r / min, and run for 6 h under the protective gas of argon to obtain a moist ultrafine crystalline powder precursor.

[0075] (3) Drying: The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm.

[0076] (4) The pre-alloyed high-entropy solid solution powder was placed in a graphite mold (φ30 mm or φ52 mm) lined with graphite paper, and then placed in a spark plasma sintering furnace. Sintering was initiated at a preset constant pressure of 40 MPa. Sintering parameters: vacuum degree below 1 Pa, sintering temperature 1135 ℃, holding time 10 min, heating rate from room temperature to 700 ℃ 55 ℃ / min, and heating rate from 700 ℃ to 1135 ℃ 95 ℃ / min. After sintering, the furnace was cooled to room temperature to obtain Co with both wear-resistant heterogeneous grains and phase structure. 39 Ni 35 Nb 14 Ti6Al4B2 high-entropy alloy.

Claims

1. A wear-resistant high-entropy alloy possessing both heterogeneous grain and heterogeneous phase structures, characterized in that: This high-entropy alloy is a single-phase high-entropy alloy, and its schematic chemical composition formula is H. 95~85 P 3~13 B2, the proportions of each element are expressed as atomic percentages; where H represents a chemically complex solid solution with non-equiatomic ratios, specifically (Co... 25 Ni 23 Cr 20 Fe 20 ), (Cr 29 Fe 27 Ni 32 Nb6) or (Co 39 Ni 35 Nb 14 Any one of (MoW), (TiV), or (TiAl); P represents the heterogeneous precipitation nucleation composition, which is any one of (MoW), (TiV), or (TiAl); B is the grain boundary stabilizing element boron; the preparation method includes the following steps: (1) Co powder, Ni powder, Cr powder, Fe powder, Nb powder, Ti powder, Al powder, V powder, Mo powder, W powder and B powder are weighed according to a preset atomic ratio and put into a planetary high-energy ball mill. Dry grinding and alloying treatment is carried out under atmospheric conditions to obtain dry supersaturated high-entropy solid solution powder. (2) Add 5% by mass of ethyl acetate as a process control agent to the dry supersaturated high-entropy solid solution powder, and put it into a planetary ball mill again for wet grinding and crystallization under the protection gas of argon to obtain a moist ultrafine crystalline powder precursor. (3) The moist ultrafine crystalline powder precursor is placed in a vacuum oven and dried at 65 °C to constant weight, and then sieved to obtain pre-alloyed high-entropy solid solution powder with a particle size in the range of 1~20 μm. (4) The pre-alloyed high-entropy solid solution powder is sintered by spark plasma to obtain a wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure.

2. The wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described in claim 1, characterized in that: In step (1), the Co powder, Ni powder, Cr powder, Fe powder, Nb powder, Ti powder, Al powder, V powder, Mo powder, and W powder are all spherical or irregular in shape, with a particle size of 10~35 μm and a purity of >99.9%.

3. The wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described in claim 1, characterized in that: In step (1), the particle size of powder B is 500 nm and the purity is >99.9%.

4. The wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described in claim 1, characterized in that: The conditions for dry grinding alloying treatment in step (1) are as follows: using cemented carbide balls with a diameter of 5-15 mm as grinding balls, a ball-to-material ratio of 4-6:1, a rotation speed of 150-250 r / min, and a running time of 15-45 h.

5. The wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described in claim 1, characterized in that: The conditions for wet grinding and crystallization in step (2) are as follows: using cemented carbide balls with a diameter of 5-15 mm as grinding balls, a ball-to-material ratio of 1.5-2.5:1, a rotation speed of 100-200 r / min, and a running time of 3-8 h.

6. The wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described in claim 1, characterized in that: The conditions for spark plasma sintering in step (4) are: vacuum degree below 1 Pa, sintering temperature 1100~1250 ℃, applied pressure 30~40 MPa, and holding time 8~15 min.

7. The wear-resistant high-entropy alloy with both heterogeneous grain and heterogeneous phase structure as described in claim 1, characterized in that: The heating process in step (4) of the spark plasma sintering process refers to a heating rate of 40~60 ℃ / min from room temperature to 700 ℃, and a heating rate of 80~100 ℃ / min from 700 ℃ to 1100~1250 ℃.

Images