Iron-based medium-entropy alloy with excellent mechanical properties in wide temperature range and preparation method thereof

Abstract

The application provides an iron-based medium-entropy alloy with excellent mechanical properties in a wide temperature range and a preparation method thereof, and the alloy contains Fe: 56.3%, Ni: 20%, Cr: 13%, Al: 9%, Mo: 1.4% and Si: 0.3% in terms of atomic percentage. The alloy ingot is subjected to cold rolling (a reduction rate is 85%) to make the alloy generate grain refinement effect due to deformation, and then is subjected to recrystallization annealing heat treatment at 800 DEG C for 10 minutes, and then is rapidly subjected to water quenching to obtain the alloy. Compared with some high-entropy alloys and traditional alloys, the experimental sample has good strength and plasticity through reasonable component configuration and preparation process, has excellent strength and uniform elongation at 298K, 77K and 973K, and is an iron-based medium-entropy alloy with excellent mechanical properties in a wide temperature range.

Description

Technical Field

[0001] This invention generally relates to the field of alloy technology, and specifically to an iron-based medium-entropy alloy with excellent mechanical properties over a wide temperature range and its preparation method. Background Technology

[0002] In recent years, with the in-depth research of materials science, medium-entropy alloys, as a new type of high-performance alloy material, have gradually attracted attention. Medium-entropy alloys have a moderate composition of elements, falling between traditional and high-entropy alloys. Their unique microstructure gives them significant advantages in mechanical properties, corrosion resistance, and high-temperature resistance. However, research on iron-based medium-entropy alloys is still in its early stages, especially in the preparation methods and performance studies of iron-based medium-entropy alloys that maintain excellent mechanical properties over a wide temperature range. Many problems remain to be solved. Therefore, developing an iron-based medium-entropy alloy with excellent mechanical properties over a wide temperature range and its preparation method is of great significance for promoting the development of materials science and meeting the needs of modern industry. Summary of the Invention

[0003] This invention aims to prepare an iron-based medium-entropy alloy with excellent mechanical properties over a wide temperature range by optimizing the alloy composition and preparation process. This alloy not only maintains excellent mechanical properties at room temperature but also exhibits good mechanical stability under both high and low temperature conditions, thus meeting the application requirements of modern industry in extreme temperature environments.

[0004] The iron-based medium-entropy alloy provided by the present invention comprises, by atomic percentage, 54%–58% Fe, 18%–22% Ni, 11%–15% Cr, 7%–11% Al, 1%–2% Mo, and 0.3%–1% Si.

[0005] Furthermore, in atomic percentages, it includes: Fe: 56.3%, Ni: 20%, Cr: 13%, Al: 9%, Mo: 1.4%, and Si: 0.3%.

[0006] This invention utilizes a specific medium-entropy alloy design concept to calculate and analyze suitable iron-based medium-entropy alloy compositions. Using Fe as the matrix reduces costs; adding Ni and Cr increases the alloy's strength and corrosion resistance; adding Al and Mo promotes solid solution strengthening; and adding Si ensures sufficient and uniform diffusion during smelting, resulting in a uniformly composed ingot. This yields a material with certain strength and toughness, maintaining performance while maintaining low cost, and showing promising prospects for industrial applications.

[0007] The preparation method of this invention uses Fe 56.3 Ni 20 Cr 13 Al9Mo1.4 Si 0.3 The medium-entropy cast alloy is cold-rolled (with a reduction rate of 85%) to induce deformation and refine the grains. It is then subjected to recrystallization annealing heat treatment at 800℃ for 10 minutes, followed by rapid water bath quenching. Attached Figure Description

[0008] Figure 1 (a1), (a2), and (a3) ​​represent Fe... 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 XRD diffraction patterns of the sample before stretching, after breaking at 298K, and after breaking at 77K.

[0009] Figure 2 (a1) and (a2) are Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 The original EBSD phase diagram and grain orientation distribution of the sample; (b1) and (b2) are Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 EBSD phase diagram and grain orientation distribution of the sample at room temperature; (c1) and (c2) are Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Low-temperature fracture EBSD phase diagram and grain orientation distribution of the sample.

[0010] Figure 3 Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 The engineering stress-strain curves of the samples at 298K, 77K and 973K respectively.

[0011] Figure 4 (a)Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 (b) Fe grain size distribution 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si0.3 FCC grain boundary angle distribution in the sample; (c)Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 BCC grain boundary angle distribution of the sample.

[0012] Figure 5 (a1)Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Macroscopic fracture diagrams of the samples at room temperature, (a2) and (a3)Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Tensile fracture morphology of the sample at room temperature; (b1)Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Macroscopic fracture diagrams of the sample under low-temperature conditions, (b2) and (b3)Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Tensile fracture morphology of the sample under low temperature environment. Detailed Implementation

[0013] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0015] Example 1 The iron-based medium-entropy alloy provided by the present invention comprises, by atomic percentage, 54%–58% Fe, 18%–22% Ni, 11%–15% Cr, 7%–11% Al, 1%–2% Mo, and 0.3%–1% Si.

[0016] Specifically, in some embodiments, the Fe content can be 54%, 55%, 56%, 57%, 58%, etc.

[0017] In some embodiments, the specific content of Ni can be 18%, 19%, 20%, 21%, 22%, etc.

[0018] In some embodiments, the specific content of Cr can be 11%, 12%, 13%, 14%, 15%, etc.

[0019] In some embodiments, the specific content of Al can be 7%, 8%, 9%, 10%, 11%, etc.

[0020] In some embodiments, the specific content of Mo can be: 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc.

[0021] In some embodiments, the specific content of Si can be: 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.

[0022] Further, as a preferred embodiment, the composition, in atomic percentages, includes: Fe: 56.3%, Ni: 20%, Cr: 13%, Al: 9%, Mo: 1.4%, and Si: 0.3%.

[0023] Specifically, this experiment used vacuum arc melting to prepare Fe. 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Medium-entropy as-cast alloy. The alloy is produced as an ingot from the furnace, followed by cold rolling (85% reduction) to deform and refine the grains. It then undergoes recrystallization annealing heat treatment at 800℃ for 10 minutes, followed by rapid water bath quenching. After these heat treatment steps, the cut samples are polished and then placed in a tensile testing machine for uniaxial tensile tests at room temperature and low temperature. After the tensile tests, a series of characterization procedures are performed to observe its microstructure and mechanical properties.

[0024] The phase composition of annealed and stretched samples was determined by X-ray diffraction (XRD). The XRD patterns were then analyzed. Figure 1 We can clearly see Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3A phase transformation occurred during stretching, with some FCC phases transforming into BCC phases, producing an effect similar to the TRIP effect, resulting in superior alloy properties after stretching. The phase distribution and grain orientation distribution of the samples before and after stretching were detected using electron backscattering (EBSD) technology. Figure 2 b1 and c1 are Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 Phase distribution after tensile fracture under two different environments. Compared with the original sample ( Figure 2 (a1) A comparison easily reveals that the content of the BCC phase significantly increased after uniaxial stretching, indicating a deformation-induced phase transformation, similar to TRIP steel. The phase transformation during stretching increased tensile strength and elongation, improving the alloy's mechanical properties, which is consistent with initial expectations. Characterization of Fe... 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 We obtained the sample. Figure 4 From the figure, we can easily see Al9Mo 1.4 The samples exhibit very fine grain sizes, with an average grain size of only 0.23 μm, which can produce significant grain refinement strengthening. The fracture type and morphology distribution of the tensile fracture surface were observed using scanning electron microscopy (SEM). Figure 5 Regardless of whether it is at low temperature or room temperature, the radial zone of the fracture surface is not particularly significant. The radial zone represents brittle fracture, thus proving that the alloy has excellent ductility and toughness in both environments.

[0025] Fe 56.3 Ni 20 Cr 13 Al9Mo 1.4 Si 0.3 The tensile stress-strain curves and microhardness of the alloy are as follows: Figure 3 As shown. Under normal temperature conditions, Al9Mo 1.4 The tensile strength and elongation are 1045 MPa and 23%, respectively; the tensile strength and elongation at low temperature are 1695 MPa and 33%, respectively; and the tensile strength and elongation at high temperature are 473 MPa and 10%, respectively.

[0026] Compared with some high-entropy alloys and traditional alloys, this invention, through reasonable composition configuration and preparation method, achieves good strength and toughness, and exhibits excellent strength and uniform elongation at 298K, 77K and 973K. It is an iron-based medium-entropy alloy with excellent mechanical properties over a wide temperature range.

[0027] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A medium-entropy iron-based alloy exhibiting excellent mechanical properties over a wide temperature range, characterized in that, The alloy comprises, by atomic percentage, 54%~58% Fe, 18%~22% Ni, 11%~15% Cr, 7%~11% Al, 1%~2% Mo, and 0.3%~1% Si. The alloy undergoes a TRIP effect during stretching, transforming from the FCC phase to the BCC phase, and has an average grain size of 0.23 μm.

2. The iron-based medium-entropy alloy with excellent mechanical properties over a wide temperature range according to claim 1, characterized in that, Based on atomic percentages, it includes: Fe: 56.3%, Ni: 20%, Cr: 13%, Al: 9%, Mo: 1.4%, Si: 0.3%.

3. A method for preparing the iron-based medium-entropy alloy with excellent mechanical properties over a wide temperature range as described in any one of claims 1-2, characterized in that, The alloy composition was prepared by vacuum arc melting. The alloy was in the form of an ingot when it came out of the furnace. It was then cold rolled to deform it and produce a grain refinement effect. The cold rolling reduction rate was 85%. Then it was subjected to recrystallization annealing heat treatment at 800°C for 10 minutes and then rapidly quenched in a water bath.

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