A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity and its preparation method and application

Abstract

The present invention discloses a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity, as well as its preparation method and application, belonging to the technical field of magnesium alloy material processing. The alloy contains an alternating dual-phase structure, which is composed of submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions; the width of the submicron-scale α-Mg flakes is less than 2 microns, and the average aspect ratio of the flakes is (4-6):1; the interior of the nanocrystalline β-Li+α-Mg mixed region is a mixed grain of lithium phase and magnesium phase with nanocrystalline grain size; nanoscale LiMgAl2 phase is precipitated at the phase interface between the submicron-scale α-Mg flakes and the nanocrystalline β-Li+α-Mg mixed region. The present invention obtains a dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity and alternating arrangement by controlling heat treatment and three-time high-frequency vibration compression technology, and simultaneously improves the stiffness (elastic modulus) and corrosion resistance of the magnesium-lithium alloy.

Description

Technical Field

[0001] The present invention relates to a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity, a preparation method and application thereof, and belongs to the technical field of magnesium alloy material processing. Background Art

[0002] As a green engineering material for the 21st century, magnesium alloys offer exceptional properties, including high specific strength and stiffness, excellent damping capacity, and superior radiation resistance. This has led to their widespread application in industries such as aerospace, automotive, 3C (computers, communications, and consumer electronics), and medical equipment. However, the hexagonal close-packed (HCP) structure of magnesium alloys provides a limited slip system during deformation, restricting their cold working properties. The addition of lithium significantly improves the properties of magnesium alloys, reducing alloy density (ρ = 1.33-1.65 g / cm³) and increasing room-temperature ductility and cold forming ability. However, the strength and corrosion resistance of Mg-Li alloys are largely dependent on the lithium content. Due to the high chemical reactivity of lithium and its tendency to oxidize at room temperature, Mg-Li alloys exhibit inferior elastic modulus and corrosion resistance compared to other magnesium alloys, severely limiting their industrial application and development.

[0003] To address these challenges, researchers have explored various strengthening methods for Mg-Li alloys, including mechanical treatments (hot rolling, extrusion, and high-pressure torsion) and alloying. [Corrosion Science 51 (2009) 2463-2472] indicates that the addition of Al to Mg-Li alloys can promote the formation of a uniform and dense Mg(OH)2 oxide film, thereby improving corrosion resistance and reducing the corrosion rate by approximately 30%. To increase the elastic modulus of metallic materials, high-modulus phases are often incorporated into the alloy's microstructure. This involves incorporating large amounts of alloying elements into the base alloy to produce intermediate compounds with higher modulus. In [Materials Characterization 244 (2024) 113180], the modulus of a Mg-5Li-4Al-1.8Zn-2.5Y-3Nd-4Dy-2Ag-0.3Zr-0.5Er alloy was successfully increased to 54.29 GPa by introducing a high-modulus Al2RE phase. However, this alloy still lags far behind the modulus of aluminum alloys, and its overly complex composition limits its practical applicability. Therefore, conventional processing techniques make it difficult to simultaneously improve the stiffness (elastic modulus) and corrosion resistance of magnesium-lithium alloys. To address the issues of insufficient stiffness (elastic modulus) and poor corrosion resistance of Mg-Li alloys, the present invention proposes a high-stiffness, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano-grain heterogeneity, its preparation method, and its application, based on the commercial LA91 magnesium-lithium alloy. Summary of the Invention

[0004] This invention provides a method for preparing a high-strength, corrosion-resistant, dual-phase magnesium-lithium alloy with micro- and nano-grain heterogeneity. Using the commercial LA91 magnesium-lithium alloy (composed of 90% magnesium, 9% lithium, and 1% aluminum) as a base, a controlled heat treatment and three-stage high-frequency vibration compression technique yield a dual-phase magnesium-lithium alloy with alternating micro (submicron-scale α-Mg flakes) and nano (nanocrystalline β-Li + α-Mg mixed regions) grain heterogeneity. Furthermore, a nanoscale LiMgAl2 phase precipitates at the phase interface. This specialized microstructure simultaneously enhances the alloy's stiffness (elastic modulus) and corrosion resistance.

[0005] At the same time, the present invention provides a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity.

[0006] At the same time, the present invention provides a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity for use in biomedicine (degradable medical devices), aerospace (satellite antennas) and other fields.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nanograin heterogeneity is disclosed. The alloy is a commercial LA91 alloy containing an alternating dual-phase α-Mg+β-Li structure, wherein the α-Mg phase is a lamellar structure with a lamellar width of less than 2 microns and an average aspect ratio of (4-6):1. The interior of the β-Li phase is a mixed grain of lithium and magnesium phases with nanocrystalline grain size, and the volume fraction of the magnesium phase is 10-20%. (The volume fraction of the magnesium phase inside the β-Li phase, i.e., the α-Mg nanoparticles, and the nanocrystalline lithium phase are calculated using Image-Pro Plus software.)

[0009] Submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions are arranged alternately, and the flake directions are approximately parallel to each other, with an angle less than 15°. Nanoscale LiMgAl2 phase precipitates at the interface between α-Mg and β-Li phases.

[0010] A method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity comprises the following steps:

[0011] S01, homogenizing the commercial LA91 alloy in a heat treatment furnace at 260-300°C for 4-6 hours, with argon protection during the holding process, and water cooling after the end of the holding period to obtain a homogenized alloy;

[0012] S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 20-30 kHz and an amplitude of 40-50 microns. The processing is stopped when the compression reaches 10-20%.

[0013] S03, the alloy processed in S02 is subjected to a second ultra-high frequency vibration compression treatment with a frequency of 40-50 kHz and an amplitude of 15-20 microns. The processing is stopped when the cumulative compression reaches 40-50%.

[0014] S04, keep the alloy processed in S03 in an oven for 20-30 minutes at a temperature of 50-60°C, and then air-cool after the end of the holding period;

[0015] In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 20-30 kHz and an amplitude of 40-50 μm. The processing was stopped when the cumulative compression reached 70-80%.

[0016] In S01, the commercial LA91 alloy is a casting alloy with an average grain size of 100 to 150 microns.

[0017] In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

[0018] The invention discloses a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity and its application in the fields of biomedicine (degradable medical devices), aerospace (satellite antennas), etc.

[0019] A degradable medical device is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to the present invention.

[0020] A satellite antenna is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to the present invention.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Through a high-frequency vibration compression (20~30kHz), the lamellar α-Mg phase in the magnesium-lithium alloy is fully refined, and a large number of dislocations and deformation bands are formed in the β-Li phase. Then, through a second ultra-high frequency micro-amplitude vibration compression (40~50kHz), the dynamic recrystallization of the β-Li phase and the dynamic precipitation of α-Mg grains inside it are promoted to form a nanocrystalline mixed structure. In addition, the dynamic precipitation of nanoscale LiMgAl2 phase at the α-Mg / β-Li phase boundary is promoted. Finally, through three high-frequency vibration compressions (20~30kHz), the submicron-scale lamellar α-Mg phase and the nanocrystalline β-Li phase mixed structure are alternately arranged to form a micro-nanocrystalline heterogeneous dual-phase magnesium-lithium alloy. This special microstructure has a significant promoting effect on improving the mechanical properties of the alloy.

[0023] (2) The elastic modulus of the alloy can reach 65.4~70.2GPa, which is better than the existing magnesium-lithium alloys with the same composition (series).

[0024] (3) Due to the formation of nanocrystals in the β-Li phase and the dynamic precipitation of α-Mg nanocrystals, the potential difference between the α-Mg phase and the β-Li phase in the original two-phase system is reduced, galvanic corrosion is suppressed, and the corrosion resistance of the alloy is significantly improved. The corrosion (degradation) rate after immersion in simulated body fluid for 7 days reaches 0.083~0.125mm / y, and the corrosion weight loss rate after immersion in 3.5wt% NaCl solution for 5 days is 0.86~1.52mm / y.

[0025] (4) The high-frequency vibration compression process of the present invention is characterized by high precision and high speed, which can improve processing efficiency. In addition, the mold can be customized according to the shape of the component to achieve near-net forming of the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a TEM photo of the micro-nano grain heterogeneous dual-phase magnesium-lithium alloy of the present invention;

[0027] Figure 2 This is a TEM photograph of the interface between α-Mg and β-Li phases of the present invention;

[0028] Figure 3 This is a diagram of α-Mg+β-Li mixed nanocrystals formed in the β-Li phase of the present invention;

[0029] Figure 4 yes Figure 3 Selected electron diffraction pattern of the middle area. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific examples. The following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Example 1

[0031] A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity is disclosed. The alloy is a commercial LA91 alloy containing an alternating dual-phase α-Mg+β-Li structure, wherein the α-Mg phase is a lamellar structure with a lamellar width of 1.5 microns and an average aspect ratio of 4:1. The interior of the β-Li phase is a mixed grain of lithium and magnesium phases with nanocrystalline grain size, with a volume fraction of the magnesium phase of 10% and a volume fraction of the lithium phase of 90%.

[0032] In this embodiment, the micro-nano grains are heterogeneous, where the "micro" refers to submicron-scale α-Mg flakes and the "nano" refers to a nanocrystalline β-Li+α-Mg mixed region. The "submicron-scale α-Mg flakes" and the "nanocrystalline β-Li+α-Mg mixed region" are heterogeneous and alternately arranged to form a dual-phase magnesium-lithium alloy. In addition, a nano-scale LiMgAl2 phase is precipitated in the phase interface region of the dual-phase magnesium-lithium alloy.

[0033] Preferably, the submicron α-Mg flakes and the nanocrystalline β-Li + α-Mg mixed region are arranged alternately and the flake directions are approximately parallel to each other, with an angle of 15°, and a nanoscale LiMgAl2 phase is precipitated at the interface between the α-Mg (i.e., the submicron α-Mg flakes) and the β-Li phase (i.e., the nanocrystalline β-Li + α-Mg mixed region).

[0034] A method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity comprises the following steps:

[0035] S01: homogenizing a commercial LA91 alloy (commercial LA91 alloy is a casting alloy with an average grain size of 150 μm) in a heat treatment furnace at 300°C for 5 hours. Argon gas was introduced during the holding process, and the alloy was water-cooled to obtain a homogenized alloy.

[0036] S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 20 kHz and an amplitude of 40 μm, and stopping the processing when the compression reaches 20%;

[0037] In S03, the alloy processed in S02 is subjected to a second ultra-high frequency vibration compression treatment with a frequency of 40 kHz and an amplitude of 15 microns. The processing is stopped when the cumulative compression reaches 50%;

[0038] S04, the alloy processed in S03 was kept in an oven at 50°C for 20 minutes, and then air-cooled after the end of the holding period;

[0039] In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 20 kHz and an amplitude of 40 μm. The processing was stopped when the cumulative compression reached 70%.

[0040] In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

[0041] The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity of this embodiment is used in the fields of biomedicine (degradable medical devices), aerospace (satellite antennas), etc.

[0042] A degradable medical device is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0043] A satellite antenna is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0044] like Figure 1 As shown, it is a TEM photograph of the micro-nano grain heterogeneous dual-phase magnesium-lithium alloy of this embodiment. The dual-phase layers are arranged alternately, and the width of the α-Mg layer is 1.5 microns, which is submicron level.

[0045] like Figure 2 As shown in FIG, it is a TEM photograph of the interface between α-Mg and β-Li phases of this embodiment. It can be confirmed that a nano-scale LiMgAl2 phase rich in Al element is precipitated at the interface.

[0046] like Figure 3 As shown, the α-Mg+β-Li mixed nano-crystals formed in the β-Li phase of this embodiment, wherein the black ones are dynamically precipitated α-Mg grains.

[0047] like Figure 4 As shown, it can be determined that nano-sized α-Mg+β-Li mixed grains exist in the alloy. Example 2

[0048] A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity is disclosed. The alloy is a commercial LA91 alloy containing an alternating dual-phase α-Mg+β-Li structure, wherein the α-Mg phase is a lamellar structure with a lamellar width of 2 microns and an average aspect ratio of 5:1. The interior of the β-Li phase is a mixed grain of lithium and magnesium phases with nanocrystalline grain size, with a volume fraction of the magnesium phase of 15% and a volume fraction of the lithium phase of 85%.

[0049] Submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions are arranged alternately, and the flake directions are approximately parallel to each other, with an angle of 13°. Nanoscale LiMgAl2 phase precipitates at the interface between α-Mg and β-Li phases.

[0050] A method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity comprises the following steps:

[0051] S01, homogenizing a commercial LA91 alloy (commercial LA91 alloy is a casting alloy with an average grain size of 120 μm) in a heat treatment furnace, maintaining the temperature at 280°C for 4 hours, with argon gas protection during the holding process, and water cooling after the end of the holding period to obtain a homogenized alloy;

[0052] S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 25 kHz and an amplitude of 40 to 50 microns, and stopping the processing when the compression reaches 15;

[0053] In S03, the alloy processed in S02 was subjected to a second ultra-high frequency vibration compression treatment with a frequency of 45 kHz and an amplitude of 18 microns. The processing was stopped when the cumulative compression reached 45%;

[0054] S04, the alloy processed in S03 was kept in an oven at 55°C for 25 minutes, and then air-cooled after the end of the holding period;

[0055] In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 23 kHz and an amplitude of 45 μm. The processing was stopped when the cumulative compression reached 75%.

[0056] In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

[0057] The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity of this embodiment is used in the fields of biomedicine (degradable medical devices), aerospace (satellite antennas), etc.

[0058] A degradable medical device is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0059] A satellite antenna is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment. Example 3

[0060] A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity is disclosed. The alloy is a commercial LA91 alloy containing an alternating dual-phase α-Mg+β-Li structure, wherein the α-Mg phase is a lamellar structure with a lamellar width of 1.6 microns and an average aspect ratio of 4.5:1. The interior of the β-Li phase is a mixed grain of lithium and magnesium phases with nanocrystalline grain size, with a volume fraction of the magnesium phase of 13% and a volume fraction of the lithium phase of 87%.

[0061] Submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions are arranged alternately, and the flake directions are approximately parallel to each other, with an angle of 10°. Nanoscale LiMgAl2 phase precipitates at the interface between α-Mg and β-Li phases.

[0062] A method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity comprises the following steps:

[0063] S01, homogenizing a commercial LA91 alloy (commercial LA91 alloy is a casting alloy with an average grain size of 130 μm) in a heat treatment furnace at 260°C for 6 hours, with argon protection during the holding process, and water cooling after the end of the holding period to obtain a homogenized alloy;

[0064] S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 30 kHz and an amplitude of 50 μm, and stopping the processing when the compression reaches 10%;

[0065] In S03, the alloy processed in S02 is subjected to a second ultra-high frequency vibration compression treatment with a frequency of 50 kHz and an amplitude of 20 microns. The processing is stopped when the cumulative compression reaches 40%;

[0066] S04, the alloy processed in S03 was kept in an oven at 60°C for 30 minutes, and then air-cooled after the end of the holding period;

[0067] In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 30 kHz and an amplitude of 50 μm. The processing was stopped when the cumulative compression reached 80%.

[0068] In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

[0069] The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity of this embodiment is used in the fields of biomedicine (degradable medical devices), aerospace (satellite antennas), etc.

[0070] A degradable medical device is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0071] A satellite antenna is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment. Example 4

[0072] A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity is disclosed. The alloy is a commercial LA91 alloy containing an alternating dual-phase α-Mg+β-Li structure, wherein the α-Mg phase is a lamellar structure with a lamellar width of 2 microns and an average aspect ratio of 6:1. The interior of the β-Li phase is a mixed grain of lithium and magnesium phases with nanocrystalline grain size, with a volume fraction of the magnesium phase of 20% and a volume fraction of the lithium phase of 80%.

[0073] Submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions are arranged alternately, and the flake directions are approximately parallel to each other, with an angle of 14°. Nanoscale LiMgAl2 phase precipitates at the interface between α-Mg and β-Li phases.

[0074] A method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity comprises the following steps:

[0075] S01: homogenizing a commercial LA91 alloy (commercial LA91 alloy is a casting alloy with an average grain size of 100 μm) in a heat treatment furnace at 270°C for 4.5 hours. Argon gas was introduced during the holding process, and the alloy was water-cooled to obtain a homogenized alloy.

[0076] S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 20 kHz and an amplitude of 50 μm, and stopping the processing when the compression reaches 10%;

[0077] In S03, the alloy processed in S02 was subjected to a second ultra-high frequency vibration compression treatment with a frequency of 44 kHz and an amplitude of 20 μm. The processing was stopped when the cumulative compression reached 50%;

[0078] S04, the alloy processed in S03 was kept in an oven at 50°C for 22 minutes, and then air-cooled after the end of the holding period;

[0079] In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 20 kHz and an amplitude of 50 μm. The processing was stopped when the cumulative compression reached 80%.

[0080] In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

[0081] The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity of this embodiment is used in the fields of biomedicine (degradable medical devices), aerospace (satellite antennas), etc.

[0082] A degradable medical device is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0083] A satellite antenna is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment. Example 5

[0084] A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity is disclosed. The alloy is a commercial LA91 alloy containing an alternating dual-phase α-Mg+β-Li structure, wherein the α-Mg phase is a lamellar structure with a lamellar width of 1.6 microns and an average aspect ratio of 5.5:1. The interior of the β-Li phase is a mixed grain of lithium and magnesium phases with nanocrystalline grain size, with a volume fraction of the magnesium phase of 18% and a volume fraction of the lithium phase of 82%.

[0085] Submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions are arranged alternately, and the flake directions are approximately parallel to each other, with an angle of 15°. Nanoscale LiMgAl2 phase precipitates at the interface between α-Mg and β-Li phases.

[0086] A method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity comprises the following steps:

[0087] S01: homogenizing a commercial LA91 alloy (commercial LA91 alloy is a casting alloy with an average grain size of 140 μm) in a heat treatment furnace at 290°C for 5.5 hours. Argon gas was introduced during the holding process, and the alloy was water-cooled after the holding period to obtain a homogenized alloy.

[0088] S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 30 kHz and an amplitude of 50 μm, and stopping the processing when the compression reaches 20%;

[0089] In S03, the alloy processed in S02 is subjected to a second ultra-high frequency vibration compression treatment with a frequency of 50 kHz and an amplitude of 20 microns. The processing is stopped when the cumulative compression reaches 50%;

[0090] S04, the alloy processed in S03 was kept in an oven at 60°C for 20 minutes, and then air-cooled after the end of the holding period;

[0091] In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 20 kHz and an amplitude of 50 μm. The processing was stopped when the cumulative compression reached 80%.

[0092] In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

[0093] The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity of this embodiment is used in the fields of biomedicine (degradable medical devices), aerospace (satellite antennas), etc.

[0094] A degradable medical device is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0095] A satellite antenna is prepared using a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to this embodiment.

[0096] Comparative Example 1

[0097] The only difference between this comparative example and Example 1 is that only one high-frequency vibration compression process is used. Specifically, the frequency is 20 kHz, the amplitude is 40 microns, and the processing is stopped when the cumulative compression amount reaches 70%.

[0098] Comparative Example 2

[0099] The only difference between this comparative example and Example 1 is that two high-frequency vibration compression processes are used. Specifically,

[0100] One high-frequency vibration compression process with a frequency of 20kHz and an amplitude of 40 microns. The process is stopped when the compression reaches 20%;

[0101] The alloy processed as above was subjected to a second ultra-high frequency vibration compression treatment with a frequency of 40 kHz and an amplitude of 15 microns. The processing was stopped when the cumulative compression amount reached 70%.

[0102] Comparative Example 3

[0103] The only difference between this comparative example and Example 1 is that three high-frequency vibration compression processes are used, but the frequency and amplitude are different from those in Example 1.

[0104] Specifically:

[0105] A high-frequency vibration compression process with a frequency of 15kHz and an amplitude of 35 microns. The process is stopped when the compression reaches 20%;

[0106] Secondary ultra-high frequency vibration compression treatment, with a frequency of 35kHz and an amplitude of 10 microns. Processing is stopped when the cumulative compression reaches 50%;

[0107] Three high-frequency vibration compression treatments are performed with a frequency of 15kHz and an amplitude of 35 microns. The processing is stopped when the cumulative compression reaches 70%.

[0108] Comparative Example 4

[0109] The only difference between this comparative example and Example 1 is that three high-frequency vibration compression processes are used, but the frequency and amplitude are different from those in Example 1.

[0110] Specifically:

[0111] One ultra-high frequency vibration compression process with a frequency of 35kHz and an amplitude of 55 microns. The process is stopped when the compression reaches 20%;

[0112] Secondary ultra-high frequency vibration compression treatment, with a frequency of 55kHz and an amplitude of 25 microns. Processing stops when the cumulative compression reaches 50%;

[0113] Three ultra-high frequency vibration compression treatments with a frequency of 35kHz and an amplitude of 55 microns are performed. The processing is stopped when the cumulative compression reaches 70%.

[0114] Comparative Example 5

[0115] The only difference between this comparative example and Example 1 is that four ultra-high frequency vibration compression treatments are used. Specifically, after step S05 is completed, the alloy processed by S05 is subjected to four ultra-high frequency vibration compression treatments with a frequency of 40 kHz and an amplitude of 15 microns. The processing is stopped when the cumulative compression amount reaches 85%.

[0116] The following performance tests were conducted on the prepared high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity:

[0117] 1. The elastic modulus of the material was measured using a TI-950 nanoindenter equipped with a Hysitron 2D sensor under a peak load of 8000 μN and a loading rate of 1600 μN / s. To ensure the reliability of the experimental data, the experiment was repeated at no fewer than 15 points on each sample surface, and the average of the final data was used as the experimental result for analysis.

[0118] 2. Weigh the sample using an electronic balance and take the average of three weighings as the original mass. Immerse the sample in a 3.5 wt.% NaCl solution at room temperature for 5 days, and use 180 g / L chromic acid solution to remove corrosion products on the alloy surface. To ensure the reliability of the results, three parallel samples of the alloy were tested for weight loss. The difference in weight before and after exposure to the corrosive environment was used to evaluate the corrosion rate, which is defined as the weight loss per unit area per unit time:

[0119]

[0120] in, is the corrosion rate (mm / year), Δ W is the weight loss (g), A is the exposed surface area (cm 2 ), t is the soaking time (h), ρ is the density of the alloy (g / cm 3 ).

[0121] 3. Use an electronic balance to weigh the sample, weigh three times and take the average value as the original mass. Place the sample and Hank's solution into a polyethylene centrifuge tube at the same time, soak for 7 days, and set up 3 parallel samples for each group. During the entire soaking test, the centrifuge tube was placed in a constant temperature water bath test box at 37±0.5℃. The corrosion products on the surface of the sample were removed by using the prepared solution (200g / L CrO3+10g / L AgNO3), and then rinsed with deionized water and ultrasonically cleaned in alcohol for 5 minutes. After natural drying, the sample with the corrosion products removed was weighed and recorded as the post-immersion mass. The corrosion rate of the soaked sample was calculated using ASTMG31:

[0122]

[0123] in, is the corrosion rate (mm / year), Δ W is the weight loss (g), A is the exposed surface area (cm 2 ), t is the soaking time (h), ρ is the density of the alloy (g / cm3 ).

[0124] In order to compare the performance of each embodiment and comparative example, each alloy was tested, and its performance is summarized in Table 1 below.

[0125] Table 1

[0126]

[0127] It should be understood that in order to streamline the present disclosure and aid understanding of one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all the features of the previously disclosed embodiments. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0128] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

[0129] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity, characterized in that: The alloy contains an alternating dual-phase structure consisting of submicron-sized α-Mg layers and nanocrystalline β-Li+α-Mg mixed regions. The width of the submicron α-Mg flakes is less than 2 microns, and the average aspect ratio of the flakes is (4-6):1; The interior of the nanocrystalline β-Li+α-Mg mixed region is a mixture of lithium and magnesium phases with nanocrystalline grain size, and the volume fraction of the magnesium phase is 10~20%; Nanoscale LiMgAl2 phase precipitates at the interface between submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions.

2. The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to claim 1, characterized in that: Submicron-scale α-Mg flakes and nanocrystalline β-Li+α-Mg mixed regions are arranged alternately, and the flake directions are approximately parallel to each other, with an angle of less than 15°.

3. The high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to claim 1, characterized in that: The elastic modulus of the alloy reaches 65.4~70.2GPa, the corrosion degradation rate after immersion in simulated body fluid for 7 days is 0.083~0.125mm / y, and the corrosion weight loss rate after immersion in 3.5wt% NaCl solution for 5 days is 0.86~1.52mm / y.

4. The method for preparing a high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to any one of claims 1 to 3, characterized in that: The following steps are involved: S01, homogenizing the commercial LA91 alloy in a heat treatment furnace at 260-300°C for 4-6 hours, with argon protection during the holding process, and water cooling after the end of the holding period to obtain a homogenized alloy; S02, subjecting the homogenized alloy processed in S01 to a high-frequency vibration compression treatment with a frequency of 20-30 kHz and an amplitude of 40-50 microns. The processing is stopped when the compression reaches 10-20%. S03, the alloy processed in S02 is subjected to a second ultra-high frequency vibration compression treatment with a frequency of 40-50 kHz and an amplitude of 15-20 microns. The processing is stopped when the cumulative compression reaches 40-50%. S04, keep the alloy processed in S03 in an oven for 20-30 minutes at a temperature of 50-60°C, and then air-cool after the end of the holding period; In S05, the alloy processed in S04 was subjected to three high-frequency vibration compression treatments with a frequency of 20-30 kHz and an amplitude of 40-50 μm. The processing was stopped when the cumulative compression reached 70-80%.

5. The preparation method according to claim 4, characterized in that In S01, the commercial LA91 alloy is a casting alloy with an average grain size of 100 to 150 microns.

6. The preparation method according to claim 4, characterized in that In S02, S03 and S05, high-frequency vibration compression is carried out under the protection of argon atmosphere.

7. Application of the high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity according to any one of claims 1 to 3 in biomedicine and aerospace.

8. The use according to claim 7, characterized in that Biomedical applications include biodegradable medical devices; aerospace applications include satellite antennas.

9. A degradable medical device, characterized in that: The alloy is prepared by using the high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity described in any one of claims 1 to 3.

10. A satellite antenna, characterized in that: The alloy is prepared by using the high-rigidity, corrosion-resistant dual-phase magnesium-lithium alloy with micro-nano grain heterogeneity described in any one of claims 1 to 3.

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