A dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles, its preparation method and applications

Abstract

This invention provides a Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy, its preparation method, and its applications. The general formula for Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy is Ti. a Zr b V c Nb d Al e -(Y2O3) f The alloy exhibits a molar percentage of 52% ≤ a ≤ 57%, 8% ≤ b ≤ 12%, 12% ≤ c ≤ 18%, 8% ≤ d ≤ 12%, 9% ≤ e ≤ 13%, and 0.02% ≤ f ≤ 0.08%, with a + b + c + d + e + f = 100%. In the as-cast state, the alloy displays a typical dendritic morphology, with a phase structure consisting of a body-centered cubic (BCC) structure and a Y₂O₃ ceramic phase. It not only possesses low density but also exhibits excellent tensile yield strength and plasticity at room temperature. Thermomechanical processing improves the size and distribution of the Y₂O₃ ceramic phase, further enhancing the alloy's yield strength.

Description

Technical Field

[0001] This invention relates to alloy technology, and more particularly to a dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles, its preparation method, and its applications. Background Technology

[0002] Driven by the increasing trend towards lightweight structural materials, lightweight high-entropy alloys gradually came into the researchers' view in 2010. As a new branch of high-entropy alloys, they possess the excellent properties of high-entropy alloys while also having the advantage of low density. In terms of performance, lightweight high-entropy alloys have characteristics such as high specific strength, excellent wear resistance, excellent corrosion resistance, resistance to high-temperature softening, and good biocompatibility. These performance advantages make lightweight high-entropy alloys highly promising for applications in aerospace, fossil energy, and biotechnology.

[0003] In the early stages of research on lightweight high-entropy alloys, the significant differences in atomic radius, electronegativity, crystal structure, and melting point among the alloying elements made it difficult to form a single solid solution structure. Most lightweight high-entropy alloys possess multiple complex structures, including a large number of brittle intermetallic compounds such as Laves phase, δ phase, α phase, β phase, and σ phase, making tensile testing impossible. Compressive properties were mostly used to characterize the strength and plasticity of the materials. Although some single-phase solid solution refractory high-entropy alloys exhibit excellent room-temperature tensile properties, their strength decreases rapidly with increasing temperature. Therefore, single-phase solid solutions are not advantageous at high temperatures. However, many multiphase refractory high-entropy alloys currently lack tensile plasticity at room temperature. Therefore, how to ensure both room-temperature tensile mechanical properties and high-temperature mechanical properties is an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high density and low tensile plasticity in current refractory high-entropy alloys by proposing a dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles. In the as-cast state, this alloy exhibits a typical dendritic morphology, and its phase structure consists of a body-centered cubic (BCC) structure and a Y2O3 ceramic phase. It not only has a low density but also exhibits excellent tensile yield strength and plasticity at room temperature. After thermomechanical processing, the size and distribution of the Y2O3 ceramic phase are improved, further enhancing the alloy's yield strength.

[0005] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles, with the general formula Tia Zr b V c Nb d Al e -(Y2O3) f The values ​​are: 52%≤a≤57%, 8%≤b≤12%, 12%≤c≤18%, 8%≤d≤12%, 9%≤e≤13%, and 0.02%≤f≤0.08%, where a+b+c+d+e+f=100%, and a, b, c, d, e, and f correspond to the molar percentages of the elements.

[0007] Furthermore, in the general formula, 54.5% ≤ a ≤ 55.5%, 9.5% ≤ b ≤ 10.4%, 14.5% ≤ c ≤ 15.6%, 9.5% ≤ d ≤ 10.3%, 9.6% ≤ e ≤ 10.5%, and 0.03% ≤ f ≤ 0.07%.

[0008] Furthermore, the Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy is a dual-phase structure composed of BCC and Y2O3 phases.

[0009] Furthermore, the density ρ of the Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy is ≤ 5.5 g / cm³. 3 The preferred density is 5.2 g / cm³. 3 .

[0010] Furthermore, the tensile yield strength of the Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy at room temperature is 1.2–1.4 GPa, and the elongation after fracture is 10–20%, with the preferred tensile yield strength being 1.3–1.4 GPa and the elongation after fracture being 15–20%.

[0011] Another objective of this invention discloses a method for preparing a Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy, comprising the following steps:

[0012] Step 1: Raw material selection: Select elemental metals Ti, Zr, V, Nb and Al, and polish their surfaces with sandpaper to remove oxide scale and stains; select Y2O3 powder and add it to the alloy ingot;

[0013] Step 2, Ingredient Preparation: Weigh the selected raw materials according to the molar ratio of each component in the general formula;

[0014] Step 3, Smelting: Place the prepared raw materials into a vacuum electric arc melting furnace and smelt them in an inert gas atmosphere. First, melt the Ti ingot, then melt the alloy raw materials and use electromagnetic stirring technology to obtain a lightweight, refractory, high-entropy alloy ingot with uniform composition.

[0015] Step 4: Thermomechanical treatment: The cast alloy ingot obtained in Step 3 is hot-rolled and then placed in a heat treatment furnace for high-temperature annealing to obtain a dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles with excellent mechanical properties [also known as TiZrVNbAl-(Y2O3) lightweight refractory high-entropy alloy].

[0016] Furthermore, the selected raw materials Ti, Zr, V, Nb, and Al have a purity greater than or equal to 99.95 wt.%.

[0017] Furthermore, the selected Y2O3 powder has a purity of 99.99 wt.% and a particle size of 10–100 nm, preferably 20–40 nm.

[0018] Furthermore, the weighing error for the raw materials is ±0.001g.

[0019] Furthermore, before smelting the alloy raw materials, the vacuum level of the electric arc furnace needs to be evacuated to 2.5 × 10⁻⁶. -3 ~3×10 -3 Pa, then purged with argon gas to -0.06 to -0.04 MPa.

[0020] Furthermore, Ti ingots are first placed in one crucible, and raw materials are placed in other crucibles. Low-melting-point Al and Ti are placed at the bottom of the crucible, Y2O3 powder is placed in the middle, and high-melting-point Zr, V and Nb are placed on top of the Y2O3 powder to prevent excessive arc impact during arc ignition, which would cause small metal particles to splash.

[0021] Furthermore, when smelting Ti ingots, smelt 2 to 4 times, each time for 50 to 70 seconds, to remove as much excess oxygen as possible from the chamber.

[0022] Furthermore, in step three, when placing the alloy raw materials, place the low-melting-point Al and Ti at the bottom of the crucible, place the Y2O3 powder in the middle, and cover the Y2O3 powder with the high-melting-point Zr, V and Nb to prevent the arc impact from being too large during arc initiation, which would cause small-sized metal particles to splash.

[0023] Furthermore, in step three, when melting the alloy raw materials, the current should be controlled at 300-500A, and the melting should be repeated 5-7 times. Each melting arc should last for 2-3 minutes to ensure that the alloy is fully melted.

[0024] Furthermore, in step three, when smelting the alloy raw materials, electromagnetic stirring technology is used, with a current frequency of 4 to 6 Hz.

[0025] Furthermore, the parameters for the thermomechanical treatment in step four are: hot rolling temperature of 500–700℃, annealing temperature of 700–900℃, annealing time of 0.5–1.5h, and water quenching.

[0026] Another objective of this invention is to disclose the application of a Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy in the field of high-temperature structural materials for aerospace.

[0027] The present invention relates to a Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy, its preparation method, and its applications, which have the following advantages compared with existing technologies:

[0028] 1) This invention selects low-density, high-melting-point refractory elements Ti, Zr, V, and Nb, as well as low-density, reactive element Al as the main components. Y2O3 rare earth oxide powder is added to the matrix via arc melting, avoiding the complexity of mechanical alloying processes. The resulting dual-phase refractory high-entropy alloy has a density ρ ≤ 5.2 g / cm³. 3 By controlling the atomic ratio of the matrix and Y2O3, a series of lightweight, refractory, high-entropy alloys were obtained.

[0029] 2) The dual-phase lightweight refractory high-entropy alloy reinforced by Y2O3 ceramic particles of the present invention is composed of BCC structure and Y2O3 ceramic phase, and exhibits good tensile plasticity at room temperature, breaking the room temperature brittleness barrier of multiphase refractory high-entropy alloy. Its thermomechanically treated alloy has a tensile yield strength of up to 1.36 GPa at room temperature and an elongation after fracture of more than 15%, which is beneficial to subsequent processing and deformation treatment.

[0030] 3) The dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles of the present invention exhibits excellent mechanical properties after thermomechanical treatment. Due to the good thermal stability of the Y2O3 ceramic phase, it can be used as a candidate material for high-temperature structural components.

[0031] In summary, this invention obtains a series of lightweight, refractory, high-entropy alloys by controlling the atomic ratio of Y2O3. The dual-phase lightweight, refractory, high-entropy alloys reinforced with Y2O3 ceramic particles of this invention have low density and excellent room-temperature mechanical properties, and are expected to realize the engineering application of refractory high-entropy alloys. Attached Figure Description

[0032] Figure 1 Example 1Ti 54.97 Zr 10.0 V 14.99 Nb 10.0 Al 10.0 -(Y2O3) 0.04 Stress-strain curves at room temperature for tensile testing of lightweight, refractory, high-entropy alloys in as-cast and thermomechanically treated states;

[0033] Figure 2 Example 1Ti 54.97 Zr 10.0 V 14.99 Nb 10.0 Al10.0 -(Y2O3) 0.04 XRD patterns of lightweight refractory high-entropy alloys in as-cast and thermomechanically treated states;

[0034] Figure 3 Example 1Ti 54.97 Zr 10.0 V 14.99 Nb 10.0 Al 10.0 -(Y2O3) 0.04 Images of the microstructure of lightweight, refractory, high-entropy alloys in as-cast and thermomechanically treated states;

[0035] Figure 4 Example 2Ti 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 Stress-strain curves at room temperature for tensile testing of lightweight, refractory, high-entropy alloys in as-cast and thermomechanically treated states;

[0036] Figure 5 Example 2Ti 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 XRD patterns of lightweight refractory high-entropy alloys in as-cast and thermomechanically treated states;

[0037] Figure 6 Example 2Ti 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 Images of the microstructure of lightweight refractory high-entropy alloys in as-cast and thermomechanically treated states. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0039] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0040] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0041] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0042] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0043] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0044] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0045] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0046] Example 1

[0047] This embodiment provides a lightweight, refractory, high-entropy alloy reinforced with a Y₂O₃ ceramic phase, the chemical formula of which is Ti. 54.97 Zr 10.0 V 14.99 Nb 10.0 Al 10.0 -(Y2O3) 0.04 The specific preparation method is as follows:

[0048] Step 1: Composition Design and Raw Material Selection: Low-density refractory elements Ti, Zr, V, Nb, and Al were selected as the main alloying elements, with trace amounts of Y₂O₃ powder added to the matrix. The purity of all selected raw materials was greater than or equal to 99.95 wt.%, and the purity of the selected Y₂O₃ powder was 99.99 wt.%, with a particle size of 30 nm. The selected elemental metals Ti, Zr, V, Nb, and Al were polished using different grades (240#, 400#, and 600#) of SiC sandpaper to remove oxide scale and stains from the raw material surfaces.

[0049] Step 2, Batching: Convert the molar percentage of the lightweight refractory high-entropy alloy to a mass percentage. Based on a total raw material mass of 50g, the weighed masses of the metallic raw materials Ti, Zr, V, Nb, Al and Y2O3 are 23.854g, 8.263g, 6.922g, 8.416g, 2.445g and 0.100g, respectively, with a weighing error of ±0.001g.

[0050] Step 3, Melting: Place the prepared raw materials from Step 2 into a copper crucible in a vacuum arc furnace. Place the low-melting-point Al and Ti at the bottom of the crucible, and the high-melting-point Nb, V, and Zr at the top. Place the Y₂O₃ powder in the middle. Evacuate to 2.5 × 10⁻⁶. -3 Pa, then fill with argon to -0.05MPa; first melt the Ti ingot, repeat the melting 5 to 7 times to eliminate excess oxygen in the electric arc furnace, then melt the alloy ingot, repeat the melting 7 times, control the melting current at 400A, each melting arc should last for 3 minutes and be supplemented with electromagnetic stirring technology, current frequency at 4Hz, to ensure that the alloy is fully mixed and uniform.

[0051] Step 4: Thermomechanical treatment: Cut the prepared alloy ingot into blocks with a thickness of 10 mm, a length of 30 mm, and a width of 20 mm. Hold the blocks at 600℃ for 10 min, then roll them with a reduction of 0.02 mm per pass and a total reduction of 85%. After rolling, anneal at 800℃ for 1 h and then water quench them.

[0052] The lightweight, refractory, high-entropy alloy (ρ = 5.16 g / cm³) reinforced with Y₂O₃ ceramic phase provided in Example 1 is described. 3 Room temperature mechanical properties and crystal structure microstructure characterization were performed on as-cast and thermomechanically treated samples. Figure 1 Example 1Ti 54.97 Zr 10.0 V 14.99 Nb 10.0 Al 10.0 -(Y2O3) 0.04 The provided lightweight refractory high-entropy alloy in as-cast and thermomechanically treated states has room temperature tensile stress-strain curves. The results show that at room temperature, the yield strength of Example 1 in the as-cast state is 1050 MPa and the elongation after fracture exceeds 15%. After thermomechanical treatment, the yield strength of the alloy exceeds 1200 MPa. Figure 2 Example 1Ti 54.97 Zr 10.0 V 14.99 Nb 10.0 Al 10.0 -(Y2O3) 0.04 The XRD pattern of the lightweight refractory high-entropy alloy shows that Example 1 has a two-phase crystal structure composed of BCC and Y2O3 phases. Electron probe microanalysis (EPMA) was performed on Example 1. Figure 3 This is Example 1Ti 54.97 Zr 10.0 V 14.99 Nb 10.0 Al 10.0 -(Y2O3) 0.04Microscopic morphology images of lightweight refractory high-entropy alloys. In Example 1, the as-cast state shows a typical dendritic morphology, with the Y2O3 phase mainly distributed at the grain boundaries. After thermomechanical treatment, the Y2O3 phase is distributed along the rolling direction, and its size also decreases.

[0053] Example 2

[0054] This embodiment describes a lightweight, refractory, high-entropy alloy reinforced with a Y₂O₃ ceramic phase, with the chemical formula Ti. 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 Its density ρ = 5.15 g / cm³ 3 The preparation method of this alloy is the same as that of Example 1.

[0055] Figure 4 Example 2Ti 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 The provided stress-strain curves of lightweight refractory high-entropy alloy in as-cast and thermomechanically treated states at room temperature show that, at room temperature, the yield strength of the as-cast alloy in Example 2 can reach 1100 MPa, while the elongation after fracture still exceeds 10%, and the yield strength in the thermomechanically treated state is as high as 1360 MPa, with an elongation after fracture exceeding 15%. Figure 5 Example 2Ti 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 The XRD pattern of the lightweight refractory high-entropy alloy shows that the diffraction pattern of Example 2 only shows diffraction peaks of the BCC crystal structure, but its microstructure exhibits a two-phase structure (e.g., Figure 6 The specific reason may be related to the size and volume fraction of the second phase; Figure 6 This is Example 2Ti 54.97 Zr 9.99 V 14.99 Nb 9.99 Al 9.99 -(Y2O3) 0.07 Microscopic morphology images of lightweight refractory high-entropy alloys. As can be seen from the images, Example 2 has a typical dendritic morphology in the as-cast state. Compared with Example 1, the grain size of Example 2 is smaller, indicating that the addition of Y2O3 will refine the grains. The microscopic morphology after thermomechanical treatment is almost the same as that of Example 1.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-phase lightweight refractory high-entropy alloy reinforced with Y₂O₃ ceramic particles, characterized in that, Ti a Zr b V c Nb d Al e -(Y2O3) f wherein 52% < a < 57%, 8% < b < 12%, 12% < c < 18%, 8% < d < 12%, 9% < e < 13% and 0.02% < f < 0.08% and a + b + c + d + e + f = 100%, wherein a, b, c, d, e and f correspond to the molar percentage of the elements, respectively; The Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy has a dual-phase structure composed of BCC and Y2O3 phases; the Y2O3 powder has a particle size of 10~100nm.

2. The dual-phase lightweight refractory high-entropy alloy reinforced with Y₂O₃ ceramic particles according to claim 1, characterized in that, The density ρ of the Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy is ≤ 5.5 g / cm³. 3 .

3. The dual-phase lightweight refractory high-entropy alloy reinforced with Y₂O₃ ceramic particles according to claim 1, characterized in that, The tensile yield strength of the Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy at room temperature is 1.2~1.4 GPa, and the elongation after fracture is 10~20%.

4. A method for preparing a dual-phase lightweight refractory high-entropy alloy reinforced with Y₂O₃ ceramic particles as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Raw material selection: Select elemental metals Ti, Zr, V, Nb and Al, and polish their surfaces with sandpaper; select Y2O3 powder and add it to the alloy ingot; Step 2, Ingredient Preparation: Weigh the selected raw materials according to the molar ratio of each component in the general formula; Step 3, Smelting: Place the prepared raw materials into a vacuum electric arc melting furnace and smelt them in an inert gas atmosphere. First, melt the Ti ingot, then melt the alloy raw materials and use electromagnetic stirring technology to obtain a lightweight, refractory, high-entropy alloy ingot with uniform composition. Step 4: Thermomechanical treatment: The cast alloy ingot obtained in Step 3 is hot rolled and then placed in a heat treatment furnace for high-temperature annealing to obtain a dual-phase lightweight refractory high-entropy alloy reinforced with Y2O3 ceramic particles.

5. The method for preparing the Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy according to claim 4, characterized in that, Step 3: Before melting the alloy raw materials, the vacuum level of the electric arc furnace needs to be evacuated to 2.5 × 10⁻⁶. -3 ~3×10 -3 Pa, then purged with argon gas to -0.06~-0.04 MPa; And / or, first place the Ti ingot in one crucible, place the raw materials in other crucibles, place the low melting point Al and Ti at the bottom of the crucible, place the Y2O3 powder in the middle, and cover the Y2O3 powder with high melting point Zr, V and Nb; And / or, when smelting Ti ingots, smelt 2 to 4 times, each smelting time is 50 to 70 seconds.

6. The method for preparing the Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy according to claim 4, characterized in that, In step three, when melting the alloy raw materials, the current should be controlled at 300~500A, and the melting should be repeated 5~7 times. Each melting arc should last for 2~3 minutes. And / or, in step three, when smelting the alloy raw materials, electromagnetic stirring technology is used, with a current frequency of 4~6Hz.

7. The method for preparing the Y₂O₃ ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy according to claim 4, characterized in that, The parameters for the thermomechanical treatment in step four are: hot rolling temperature 500~700℃, annealing temperature 700~900℃, annealing time 0.5~1.5h, and water quenching.

8. The use of the Y2O3 ceramic particle-reinforced dual-phase lightweight refractory high-entropy alloy as described in any one of claims 1-3 in the field of high-temperature structural materials for aerospace.

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