Lightweight high-strength multi-principal-element alloys with net-like nanocrystalline ribbons prepared by cold rolling process

Abstract

The application relates to a new type of lightweight high-strength multi-principal-element alloy capable of preparing net-shaped nanocrystalline strips through a cold rolling process and belongs to the multi-principal-element alloy field. A lightweight multi-principal-element alloy with a density lower than 5.3 g*cm ‑3 The alloy composition is composed of Ti, V, Zr and Al elements. The as-cast alloy is subjected to homogenization heat treatment of 1200 DEG C / 2 hours / water cooling and cold rolling deformation of 80% reduction, and net-shaped nanocrystalline strips are prepared in the alloy organization. The new type of alloy has excellent strength and plasticity matching, the tensile strength of the cold rolled state reaches 1574.9 MPa, the yield strength reaches 1441.5 MPa, and the elongation reaches 9.5%.

Description

Technical Field

[0001] This invention relates to a lightweight, high-strength multi-principal-element alloy that produces a network of nanocrystalline ribbons through a cold rolling process, belonging to the field of multi-principal-element alloys. Background Technology

[0002] Against the backdrop of global warming and energy shortages, the development of lightweight metallic structural materials with a good balance of strength and ductility is of significant practical importance. Alloy composition design and microstructure control are two decisive factors determining the mechanical properties of metallic structural materials. Multi-principal element alloys, as a novel alloy design concept, offer broader development prospects for metallic structural materials due to their multi-principal element composition. Over the past decade, the development of multi-principal element alloys has mainly focused on refractory element-based BCC multi-principal alloys and CrMnFeCoNi-based FCC multi-principal alloys. These alloys have very high densities, severely limiting their application prospects in aerospace and new energy lightweighting fields. Therefore, designing and developing lightweight multi-principal alloy systems composed of low-density elements has become a research hotspot in the field of multi-principal alloys.

[0003] Subsequent heat treatment and deformation of as-cast alloys are effective means to improve alloy properties. Introducing nanocrystals and high-density dislocations into the alloy microstructure through drastic deformation can significantly improve the alloy's strength. However, the formation of nanocrystals or high-density dislocations can severely damage the alloy's plasticity, and the drastic plastic deformation method for preparing bulk nanocrystals is difficult to industrialize. Therefore, overcoming the low plasticity and machinability of dislocation- and nanocrystal-reinforced metallic materials is a major challenge currently facing researchers in the field of metallic materials. This invention patent provides a novel lightweight, high-strength multi-principal element alloy that can be prepared by cold rolling to produce a network of nanocrystalline ribbons. Its characteristic is that it combines the multi-principal element alloy design concept with conventional cold deformation processes, and prepares a lightweight multi-principal element alloy (5.3 g*cm³) reinforced with network nanocrystalline ribbons through cold rolling. -3 It exhibits a good balance of strength and plasticity without the need for subsequent heat treatment. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high density and low specific strength in current multi-principal element alloys by providing a lightweight, high-strength multi-principal element alloy prepared by cold rolling process using network nanocrystalline ribbons. The TiVZrAl-based lightweight multi-principal element alloy sheet reinforced with network nanocrystalline ribbons exhibits excellent comprehensive properties and will have important applications in the aerospace field.

[0005] The objective of this invention is achieved through the following technical solution.

[0006] A lightweight and high-strength multi-principal-element alloy composed of four elements: Ti, V, Zr, and Al. a V b Zr c Ald a, b, c, and d are the atomic percentages of the four elements; where 50≤a≤60, 25≤b≤35, 10≤c≤15, 4≤d≤7, and a+b+c+d+e=100;

[0007] A cold rolling process for preparing the above-mentioned multi-principal element alloy network nanocrystalline ribbon structure includes the following steps:

[0008] Step 1: Select four elements—Ti, V, Zr, and Al—and weigh them precisely according to their atomic percentages. Obtain a TiVZrAl alloy ingot using a conventional vacuum arc melting method. To ensure the homogeneity of the composition of the multi-principal element master alloy ingot, the alloy is repeatedly melted eight times.

[0009] Step Two: The as-cast TiVZrAl alloy obtained in Step One is subjected to homogenization heat treatment. The heat treatment process is to hold at 1200℃ for 2 hours and then water-cool.

[0010] Step 3: The homogenized alloy obtained in Step 3 is cold rolled. The first cold rolling deformation is 10%, followed by repeated rolling with a deformation of 15-20%, and finally the total cold rolling deformation is controlled to be 80-85%.

[0011] Beneficial effects

[0012] This invention, through rational composition design and conventional arc melting methods, prepares a TiVZrAl-based lightweight multi-principal-element alloy with a density below 5.3 g / cm³. -3 Subsequently, a microstructure with a network of nanocrystalline ribbons was prepared through high-temperature homogenization and cold rolling. This novel network of nanocrystalline ribbons reduces the dislocation density within the deformation bands while forming nanocrystals, and combined with the heterostructure strengthening effect caused by grain size differences, significantly improves the mechanical properties of the alloy. Under rolled conditions, its tensile strength reaches 1574.9 MPa, its yield strength reaches 1441.5 MPa, and its elongation reaches 9.5%, with its comprehensive mechanical properties significantly higher than other multi-principal element alloys. Attached Figure Description

[0013] Figure 1 It is Ti 52 V 29 Zr 14 Microstructure of Al5 alloy after homogenization and 80% cold rolling; Figure a is EBSD BC image; Figure b is transmission electron microscope image (TEM image) of nanocrystals.

[0014] (Note: Figure 1 The black banded structure in a is a nanocrystal band. Because the size of the nanocrystal (~20nm) is smaller than the minimum step size of EBSD, it is displayed as an unidentified black band. Figure 1b represents the morphology inside the nanocrystals.

[0015] Figure 2 It is Ti 52 V 29 Zr 14 Backscattered electron diffraction quality diagram (EBSD BC diagram) of Al5 alloy after homogenization treatment;

[0016] Figure 3 It is Ti 52 V 29 Zr 14 Microstructure of Al5 alloy after homogenization and 50% cold rolling; Figure a is the EBSD BC image; Figure b is the TEM image of the deformation zone;

[0017] Figure 4 It is Ti 52 V 29 Zr 14 Tensile stress-strain curves of Al5 alloy under different conditions. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example 1

[0020] The lightweight multi-principal element alloy of this embodiment has the following atomic percentage composition: Ti 52 V 29 Zr 14 Al5. An alloy ingot was obtained by conventional vacuum arc melting of pure metallic titanium, vanadium, zirconium, and aluminum with a purity exceeding 99.9%. The alloy density was 5.16 g / cm³. -3 The as-cast alloy was then homogenized and cold-rolled. First, homogenization was performed, with a heat treatment temperature of 1200℃, a holding time of two hours, and water cooling. Then, the homogenized multi-principal element alloy was cold-rolled. The first cold rolling deformation was 10%, followed by repeated rolling with a deformation of 15%, ultimately controlling the total cold rolling deformation to 80%. Its microstructure diagram is shown below. Figure 1 As shown, a large number of network-like nanocrystals are generated in the alloy matrix.

[0021] Tensile mechanical properties of cold-rolled multi-principal alloys were tested at room temperature, and their tensile stress-strain curves are shown below. Figure 4 As shown, the tensile strength reaches 1574.9 MPa, the yield strength reaches 1441.5 MPa, and the elongation reaches 9.5%.

[0022] Example 2

[0023] The lightweight multi-principal element alloy of this embodiment has the following atomic percentage composition: Ti 55V 27 Zr 13 Al5. An alloy ingot was obtained by conventional vacuum arc melting of pure metallic titanium, vanadium, zirconium, and aluminum with a purity exceeding 99.9%. The alloy density was 5.11 g / cm³. -3 The as-cast alloy was then homogenized and cold-rolled. First, homogenization was performed, with a heat treatment temperature of 1200℃, a holding time of two hours, and water cooling. Then, the homogenized multi-principal element alloy was cold-rolled. The first cold-roll deformation was 10%, followed by repeated rolling with a deformation of 15%, ultimately controlling the total cold-roll deformation to 80%.

[0024] Tensile mechanical properties of the cold-rolled multi-principal alloy were tested at room temperature. The tensile strength reached 1556.8 MPa, the yield strength reached 1423.4 MPa, and the elongation reached 10.0%.

[0025] Example 3

[0026] The lightweight multi-principal element alloy of this embodiment has the following atomic percentage composition: Ti 50 V 30 Zr 15 Al5. An alloy ingot was obtained by conventional vacuum arc melting of pure metallic titanium, vanadium, zirconium, and aluminum with a purity exceeding 99.9%. The alloy density was 5.2 g / cm³. -3 The as-cast alloy was then homogenized and cold-rolled. First, homogenization was performed, with a heat treatment temperature of 1200℃, a holding time of two hours, and water cooling. Then, the homogenized multi-principal element alloy was cold-rolled. The first cold-roll deformation was 10%, followed by repeated rolling with a deformation of 15%, ultimately controlling the total cold-roll deformation to 80%.

[0027] Tensile mechanical properties of the cold-rolled multi-principal alloy were tested at room temperature, and the tensile strength reached 1589.8 MPa, the yield strength reached 1460.4 MPa, and the elongation reached 8.8%.

[0028] Comparative Example 1

[0029] The lightweight multi-principal-element alloy of this embodiment has the same alloy composition as in Example 1. An alloy ingot was obtained by conventional vacuum arc melting of pure metallic titanium, vanadium, zirconium, and aluminum with a purity exceeding 99.9%, resulting in an alloy density of 5.16 g / cm³. -3 It was then subjected to a homogenization heat treatment at 1200℃ for two hours, followed by water cooling. Its microstructure is as follows: Figure 2 As shown.

[0030] The tensile mechanical properties of the homogenized multi-principal-element alloy were tested at room temperature, and its tensile stress-strain curves are shown below. Figure 4As shown, the tensile strength reaches 975.5 MPa, the yield strength reaches 977.6 MPa, and the elongation reaches 26.3%.

[0031] Comparative Example 2

[0032] The lightweight multi-principal-element alloy of this embodiment has the same alloy composition as in Example 1. An alloy ingot was obtained by conventional vacuum arc melting of pure metallic titanium, vanadium, zirconium, and aluminum with a purity exceeding 99.9%, resulting in an alloy density of 5.16 g / cm³. -3 The as-cast alloy was then homogenized and cold-rolled. First, homogenization was performed, with a heat treatment temperature of 1200℃, a holding time of two hours, and water cooling. Then, the homogenized multi-principal element alloy was cold-rolled. The first cold-roll deformation was 10%, followed by repeated rolling with a deformation of 15%, ultimately controlling the total cold-roll deformation to 50%. Its microstructure is shown in the diagram below. Figure 3 As shown, a large number of deformation bands are generated in the alloy matrix, and no nanocrystals are observed.

[0033] Tensile mechanical properties of cold-rolled multi-principal alloys were tested at room temperature, and their tensile stress-strain curves are shown below. Figure 4 As shown, the tensile strength reaches 1291.0 MPa, the yield strength reaches 1230.7 MPa, and the elongation reaches 10.6%.

[0034] The above embodiments and two comparative examples yielded Ti with 80% cold rolling, homogenized state, and 50% cold rolling, respectively. 52 V 29 Zr 14 Al5 multi-principal element alloy. Comparing the mechanical properties of the homogenized alloy (Comparative Example 2) and the 50% cold-rolled alloy (Comparative Example 3), the Ti after cold deformation... 52 V 29 Zr 14 The strength of the Al5 multi-principal element alloy is significantly improved, while its plasticity is significantly reduced, due to the high-density dislocations generated during cold rolling. With further increases in cold rolling deformation, the tensile strength of the 80% cold-rolled alloy (Example 1) increases by 283.9 MPa, and the yield strength increases by 210.8 MPa, while the plasticity does not decrease significantly. Therefore, the Ti alloy with 80% reduction in cold rolling... 52 V 29 Zr 14 Al5 multi-principal alloys possess the best strength-plasticity balance, and their excellent comprehensive mechanical properties are attributed to the reinforcement of the network nanocrystals in the microstructure.

[0035] It should be noted that the above embodiments are merely typical specific implementations of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the technical scope of the present invention should be included within the scope of protection of the present invention. Contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A lightweight, high-strength multi-principal-element alloy with a network of nanocrystalline ribbons prepared by cold rolling process, characterized in that: It consists of a network of nanoscale grains and microscale grains; its elemental composition is Ti. a V b Zr c Al d a, b, c, and d are the atomic percentages of the four elements, where 50 ≤ a ≤ 60, 25 ≤ b ≤ 35, 10 ≤ c ≤ 15, 4 ≤ d ≤ 7, and a + b + c + d + e = 100.

2. The method for preparing the lightweight, high-strength multi-principal-element alloy as described in claim 1, characterized in that: Includes the following steps: Step 1: Select four elements, Ti, V, Zr and Al, weigh them accurately according to atomic percentage, and obtain TiVZrAl multi-principal element alloy ingots using conventional vacuum arc melting method; to ensure uniform composition of the multi-principal element alloy master alloy ingot, the alloy is repeatedly melted eight times. Step 2: The as-cast TiVZrAl alloy obtained in Step 1 is subjected to homogenization heat treatment. The heat treatment process is to hold at 1200℃ for 2 hours and then water-cool to obtain a homogenized alloy. Step 3: The homogenized alloy obtained in Step 2 is subjected to multi-pass cold rolling. The deformation amount of the first cold rolling is less than or equal to 10%, and the deformation amount of the second and subsequent cold rolling is 15~20%. Finally, the total deformation amount of cold rolling is controlled to be 80~85%; a lightweight, high-strength multi-principal element alloy is obtained.

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