Magnesium-lithium material ultrathin plate and forging-rolling composite preparation method thereof

Abstract

The invention discloses a magnesium-lithium material ultrathin plate and a forging-rolling composite preparation method thereof, and relates to the technical field of metal-based composite materials, and the magnesium-lithium material comprises the following components (in percentage by mass): 1-15% of Li, 0.5-6% of Al, 0.5-6% of Zn, 0.1-3% of rare earth elements, 4-20% of reinforced particles, and the balance of Mg and inevitable impurities. The preparation method comprises the following steps: 1) composite ball milling pretreatment and vacuum stirring casting; the method comprises the following steps of (1) carrying out heat treatment, (2) carrying out homogenizing heat treatment, (3) carrying out free forging and (4) carrying out multi-pass rolling and intermediate annealing.The method is suitable for preparing the high-strength and high-modulus magnesium-lithium material ultrathin plate with the thickness of 0.5-1.5 mm, the forming problems of particle falling, edge cracking and the like in the magnesium-lithium material machining process are solved, and the prepared magnesium-lithium material ultrathin plate is good in formability and has excellent elastic modulus and strength.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composite technology, specifically to an ultrathin magnesium-lithium material plate and its forging-rolling composite preparation method. Background Technology

[0002] Magnesium-lithium alloys are among the lightest known metallic structural materials, possessing advantages such as low density, high specific strength and stiffness, and good vibration damping performance, making them promising for applications in aerospace and other fields. However, due to the inherent properties of the material, achieving a synergistic improvement in both strength and stiffness remains a technical challenge for the industry.

[0003] To improve the mechanical properties of magnesium-lithium alloys, researchers have employed the method of adding alloying elements for strengthening. By introducing small amounts of Al and Zn elements into the alloy, solid solution and precipitation strengthening mechanisms are used to enhance material properties; adding trace amounts of rare earth elements refines the grains and effectively improves the alloy's thermal stability. Although these methods optimize alloy properties to some extent, the strengthening effect is relatively limited, especially in achieving a significant increase in material stiffness.

[0004] To overcome this bottleneck, introducing high-modulus ceramic particles as reinforcing phases has become an effective way to improve the specific modulus of magnesium-lithium alloys. Carbide and boride ceramic particles, represented by TiB2 and SiC, possess high elastic modulus and high strength. When added as reinforcing phases to magnesium-lithium alloys, they can significantly improve the Young's modulus and strength of the material. For example, Chinese invention patent CN111730059B, "A High Volume Fraction Ultrafine Particle Reinforced Mg-Li Based Composite Material and Its Preparation Method," uses an equal-diameter angular hot extrusion method to prepare magnesium-lithium materials.

[0005] However, it is worth noting that the introduction of high-content ceramic particles has also triggered a series of new problems, including particle agglomeration, interfacial debonding, and processing cracks. These problems are particularly prominent when preparing ultrathin magnesium-lithium materials with a thickness of less than 1.5 mm. Frequent edge cracking and matrix cracking along particle interfaces during rolling severely restrict the application of high-particle-content magnesium-lithium materials in thin-plate structural components. Currently, related preparation processes are mostly limited to hot rolling or extrusion of low-particle-content materials, making it difficult to directly apply to magnesium-lithium materials with high reinforcing particle content. Furthermore, existing technologies generally lack systematic control strategies for microstructure, failing to effectively solve the deformation coordination problem of high-particle-content magnesium-lithium materials during thin-plate preparation.

[0006] Therefore, there is an urgent need to develop a method for preparing ultrathin sheets of magnesium-lithium materials with high reinforcing content, so as to obtain ultrathin sheets of magnesium-lithium materials with good forming quality and high strength and high modulus properties, thereby meeting the urgent needs of key structural components for "ultra-lightweight, high modulus and high strength" materials. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide an ultrathin magnesium-lithium material plate and a method for preparing the forging-rolling composite.

[0008] The objective of this invention is achieved through the following technical solution: <First Aspect> A magnesium-lithium ultrathin plate material, by mass percentage, comprises Li: 1~15%, Al: 0.5~6%, Zn: 0.5~6%, RE: 0.1~3%, reinforcing particles: 4~20%, with the balance being Mg and unavoidable impurities.

[0009] As one implementation, the RE is one or more of Y, Gd, Er, Nd, and Yb.

[0010] As one implementation, the reinforcing particles are one or more of TiB2, SiC, and B4C.

[0011] As one implementation, the D50 of the reinforcing particles is 1~10μm.

[0012] As one implementation, the mass ratio of the reinforcing particles to Al is 7~1:1.

[0013] As one implementation, the magnesium-lithium ultrathin plate material, by mass percentage, comprises Li: 1~5.7%, Al: 0.5~6%, Zn: 4~6%, RE: 0.1~1%, reinforcing particles: 4~15%, with the balance being Mg and unavoidable impurities.

[0014] As one implementation, the magnesium-lithium ultrathin plate material, by mass percentage, comprises Li: 5.7~10.3%, Al: 1.5~4%, Zn: 0.5~4%, RE: 1~3%, reinforcing particles: 10~20%, with the balance being Mg and unavoidable impurities.

[0015] As one implementation, the magnesium-lithium material ultrathin plate material, by mass percentage, comprises Li: 10.3~15%, Al: 0.5~4%, Zn: 0.5~4%, RE: 0.1~1%, reinforcing particles: 10~20%, and the balance being Mg and unavoidable impurities.

[0016] As one implementation, the thickness of the magnesium-lithium ultrathin plate material is 0.5~1.5mm.

[0017] As one implementation, the ultrathin magnesium-lithium material plate has an elastic modulus of 50~78GPa, a yield strength of 364~385MPa, a tensile strength of 405~426MPa, and an elongation of 6~12%.

[0018] As one implementation, the magnesium-lithium ultrathin plate material, when the Li content is 1~5.7% by mass, has an elastic modulus of 50~65GPa, a yield strength of 364~375MPa, a tensile strength of 405~415MPa, and an elongation of 10~12%.

[0019] As one implementation, the magnesium-lithium ultrathin plate material, when the Li content is 5.7-10.3% by mass, has an elastic modulus of 65-73 GPa, a yield strength of 380-385 MPa, a tensile strength of 415-426 MPa, and an elongation of 8-10%.

[0020] As one implementation, the magnesium-lithium ultrathin plate material, when the Li content is 10.3-15% by mass, has an elastic modulus of 73-78 GPa, a yield strength of 375-385 MPa, a tensile strength of 405-415 MPa, and an elongation of 6-8%.

[0021] <Second aspect> This invention provides a method for preparing the above-mentioned magnesium-lithium material ultrathin plate, comprising the following steps: S1. The reinforcing particles and Al powder are ball-milled to obtain composite powder, which is then cold-pressed to obtain preforms. The preforms are then added to the vacuum molten liquid of other raw materials, kept warm and mechanically stirred until the preforms are completely melted and dispersed. Finally, they are cast to obtain ingots. S2. The ingot is homogenized to obtain a homogenized billet; S3. The homogenized billet is subjected to free forging to obtain a medium-thick plate. S4. The medium-thick plate is subjected to multiple rolling processes, and intermediate annealing is performed between the multiple processes to obtain the magnesium-lithium material ultrathin plate.

[0022] As one implementation scheme, in step S1, the parameters of the ball mill are: rotation speed 200~400 rpm, time 4~10h.

[0023] As one implementation scheme, in step S1, the parameters of the cold pressing are: pressure 15~20MPa, time 15~30min.

[0024] This invention directly uses reinforcing particles and Al powder to prepare preforms. If reinforcing particles are added during alloy preparation to react and form reinforcing particles, such as through a molten salt reaction, the TiB2 formation efficiency is not high, resulting in a low particle content. The Al-TiB2 particle content is usually no more than 5%-10%, and the Al content in the magnesium alloy of this invention is limited. Calculations show that to obtain an intermediate alloy with the TiB2 particle content level of this invention, the required molten salt mass is even much higher than the melt itself, making it impossible to maintain a normal reaction process. Therefore, it is practically difficult to effectively add a sufficient amount of reinforcing material; the amount that can be added is usually less than 3%, which cannot produce an effective increase in Young's modulus.

[0025] As one implementation scheme, in step S1, all raw materials except Al and reinforcing materials are heated to 660~700℃ and vacuum melted to obtain the vacuum melt liquid. The vacuum melting is carried out under high-purity argon gas (500Pa).

[0026] In some embodiments, in step S1, all raw materials except Al and reinforcing materials are heated to 660~590°C for vacuum melting to obtain the vacuum melt.

[0027] As one implementation scheme, in step S1, after the preform is completely melted, the temperature is adjusted to 700~750℃ for casting.

[0028] As one implementation scheme, in step S2, the homogenization treatment parameters are: temperature 300~400℃, time 2~5h. Excessive homogenization time for magnesium-lithium materials leads to significant aging softening. Even if it effectively improves plastic deformation capacity, the strength of the resulting thin sheet will be relatively low.

[0029] As one implementation scheme, in step S3, the parameters for free forging are: deformation temperature 200~350℃, and plastic deformation amount not less than 60%.

[0030] In some embodiments, in step S3, the amount of plastic deformation during free forging is 60% to 70%.

[0031] Free forging with large deformation can eliminate casting defects and particle agglomeration in magnesium-lithium materials, which is beneficial for defect control and process stability during subsequent rolling.

[0032] As one implementation scheme, in step S4, the parameters of the multi-pass rolling are: rolling temperature 150~200℃, rolling reduction rate per pass 5%~10%, and thickness reduction per pass 0.25~2mm, preferably 0.25~1.5mm.

[0033] As one implementation scheme, in step S4, when the deformation reaches 50%~60% and 80%~90% in the multi-pass rolling, intermediate annealing is performed at a temperature of 250~300℃ for 0.5~1h.

[0034] Magnesium-lithium alloys have low melting points and high oxidation tendency. Generally, the heat treatment temperature is below 350℃, otherwise there is a risk of oxidation delithiation and combustion.

[0035] Compared with the prior art, the present invention has the following beneficial effects: 1) By using ball milling pretreatment of reinforced particles and Al powder and vacuum stirring casting technology, the wettability and dispersibility of the reinforcing phase in the melt are significantly improved. The particles are uniformly distributed in the solidified structure and the interface is tightly bonded, effectively avoiding the risk of particle agglomeration and shedding under high volume fraction conditions. 2) During the homogenization process, magnesium-lithium materials can induce the formation of softening precipitates. These precipitates can coordinate the strain distribution in local stress concentration areas, laying the foundation for the subsequent plastic processing and forming performance of magnesium-lithium materials. 3) A multi-level microstructure control method was established through a composite preparation path of free forging and multi-pass rolling, which breaks down and refines the matrix grains and improves the distribution of reinforcing particles. Intermediate annealing promotes local recrystallization and strain recovery, significantly improving deformation coordination and forming stability during the rolling process; 4) The method for preparing magnesium-lithium alloy ultrathin plates provided by this invention shows good applicability to α, α+β, and β phase systems in magnesium-lithium alloys. Through process control of this invention, the material properties of magnesium-lithium alloy ultrathin plates with different phase systems can be improved, greatly expanding the scope of technology applications and providing a general solution for the high-performance preparation of magnesium-lithium alloy ultrathin plates with different composition systems. Attached Figure Description

[0036] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A flowchart of the forging and rolling composite preparation method of magnesium-lithium material ultrathin plate provided by the present invention. Detailed Implementation

[0037] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0038] This specific embodiment provides a method for preparing ultrathin magnesium-lithium material plates by forging and rolling composite, such as... Figure 1 As shown, the steps are as follows: S1. The reinforcing particles and Al powder are ball-milled to obtain composite powder, which is then cold-pressed to obtain a preform. Subsequently, it is added to the alloy solution for vacuum stirring and casting to obtain magnesium-lithium material ingots. S2. Homogenization treatment of magnesium-lithium material ingots, homogenization temperature 300~400℃, time 2~5h; S3. Free forging of the homogenized magnesium-lithium material; S4. Multi-pass rolling forming, with a thickness reduction of 0.5~2mm per pass and a rolling temperature of 150~200℃.

[0039] Furthermore, in step S3, the free forging deformation temperature is 200~350℃, and multi-directional upsetting and elongation are alternated during forging, with plastic deformation exceeding 60%.

[0040] Furthermore, in step S4, the rolling reduction rate for each pass is 5% to 10%, and the rolling temperature is 150 to 200°C.

[0041] Furthermore, in step S4, two intermediate annealing processes are performed during rolling, with an annealing temperature of 250~300℃ and an annealing time of 0.5~1h.

[0042] The final product is an ultrathin magnesium-lithium material plate with a thickness of 0.5mm to 1.5mm, which has excellent properties of high strength and high modulus.

[0043] The forging and rolling composite preparation method of magnesium-lithium material ultrathin plates is described in detail below through several examples and comparative examples.

[0044] Example 1 In this embodiment, the raw materials, by mass percentage, are Li 15%, Al 4%, Zn 2%, Y 0.5%, TiB2 particles 20%, and the balance is Mg. The D50 of the TiB2 particles is 5 μm.

[0045] A method for preparing ultrathin magnesium-lithium material plates by forging and rolling, comprising the following steps: S1, Vacuum Stirring Casting TiB2 particles and Al powder at a mass ratio of 5:1 were ball-milled to obtain composite powder. The ball-milled composite powder was then cold-pressed to obtain preforms. The ball milling speed was 400 rpm and the ball milling time was 8 h. The cold pressing pressure was 30 MPa and the cold pressing time was 15 min. In a vacuum electromagnetic induction furnace, the vacuum is evacuated to 10 Pa, and high-purity argon gas is introduced at 500 Pa. The raw materials, pure Mg, pure Li, pure Zn, and Mg-Y master alloy, are heated to 660°C. After they are completely melted, a preform is added, and the mixture is kept at this temperature and then mechanically stirred at a speed of 400 rpm for 0.5 h. The mixture is then heated to 700°C for casting to obtain magnesium-lithium material ingots.

[0046] S2, Homogenization treatment The ingot was subjected to homogenization heat treatment by holding it at 350℃ for 5 hours.

[0047] S3, Free Forging At a deformation temperature of 350℃, a forging process involving alternating multi-directional upsetting and elongation is employed to induce 60% plastic deformation in the homogenized billet.

[0048] S4, multi-pass rolling process A four-roll reversible rolling mill was used, with a rolling temperature of 200℃ and a reduction rate of 10% per pass. When the deformation reached 50% and 80%, the magnesium-lithium material sheet was subjected to intermediate annealing at a temperature of 300℃ for 1 hour, ultimately obtaining a high-strength, high-modulus ultrathin magnesium-lithium material sheet with a thickness of 0.5mm.

[0049] No defects such as edge cracking or particle detachment occurred in the sheet during the processing. The prepared magnesium-lithium material ultrathin sheet has good forming performance and high strength and high modulus mechanical properties, as shown in Table 1.

[0050] Example 2 In this embodiment, the raw materials, by mass percentage, are Li 3%, Al 5%, Zn 6%, Yb 0.5%, SiC particles 5%, and the balance is Mg. The D50 of the SiC particles is 1 μm.

[0051] A method for preparing ultrathin magnesium-lithium material plates by forging and rolling, comprising the following steps: S1, Vacuum Stirring Casting SiC particles and Al powder at a mass ratio of 1:1 were ball-milled to obtain composite powder. The ball-milled composite powder was then cold-pressed to obtain preforms. The ball milling speed was 400 rpm and the ball milling time was 10 h. The cold pressing pressure was 20 MPa and the cold pressing time was 30 min. In a vacuum electromagnetic induction furnace, the vacuum is evacuated to 5 Pa, and high-purity argon gas is introduced at 500 Pa. The raw materials, pure Mg, pure Li, pure Zn, and Mg-Yb master alloy, are heated to 680°C. After they are completely melted, a preform is added, and the mixture is kept at this temperature and then mechanically stirred at 600 rpm for 0.5 h. The mixture is then heated to 750°C for casting to obtain magnesium-lithium material ingots.

[0052] S2, Homogenization treatment The ingot was subjected to homogenization heat treatment by holding it at 300℃ for 4 hours.

[0053] S3, Free Forging At a deformation temperature of 200℃, a forging process involving alternating multi-directional upsetting and elongation is employed to induce 70% plastic deformation in the homogenized billet.

[0054] S4, multi-pass rolling process A four-roll reversible rolling mill was used with a rolling temperature of 200℃ and a reduction rate of 10% per pass. When the deformation reached 60% and 90%, the magnesium-lithium material sheet was subjected to intermediate annealing at a temperature of 250℃ for 0.5 hours, ultimately obtaining a high-strength, high-modulus ultrathin magnesium-lithium material sheet with a thickness of 1.5 mm.

[0055] No defects such as edge cracking or particle detachment occurred in the sheet during the processing. The prepared magnesium-lithium material ultrathin sheet has good forming performance and high strength and high modulus mechanical properties, as shown in Table 1.

[0056] Example 3 In this embodiment, the raw materials, by mass percentage, are Li 8%, Al 4%, Zn 2%, Er 2%, B4C particles 15%, and the balance is Mg. The D50 of the B4C particles is 10 μm.

[0057] A method for preparing ultrathin magnesium-lithium material plates by forging and rolling, comprising the following steps: S1, Vacuum Stirring Casting S11. B4C particles with a mass ratio of 15:4 and Al powder are ball-milled to obtain composite powder. The ball-milled composite powder is then cold-pressed to obtain preforms. The ball milling speed is 400 rpm, the ball milling time is 10 h, the cold pressing pressure is 20 MPa, and the cold pressing time is 15 min. S12. In a vacuum electromagnetic induction furnace, the vacuum is evacuated to 5 Pa, and high-purity argon gas is repeatedly applied at 500 Pa. The raw materials, pure Mg, pure Li, pure Zn, and Mg-Er master alloy, are heated to 690℃. After they are completely melted, a preform is added, and the mixture is kept at this temperature and then mechanically stirred at 800 rpm for 1 hour. After stirring, the temperature is raised to 720℃ for casting to obtain magnesium-lithium material ingots.

[0058] S2, Homogenization treatment The ingot was subjected to homogenization heat treatment by holding it at 400℃ for 2 hours.

[0059] S3, Free Forging At a deformation temperature of 300℃, a forging process involving alternating multi-directional upsetting and elongation is employed to induce 65% plastic deformation in the homogenized billet.

[0060] S4, multi-pass rolling process A four-roll reversible rolling mill was used with a rolling temperature of 175℃ and a reduction rate of 10% per pass. When the deformation reached 50% and 90%, the magnesium-lithium material sheet was subjected to intermediate annealing at a temperature of 300℃ for 0.5 hours, ultimately obtaining a high-strength, high-modulus ultrathin magnesium-lithium material sheet with a thickness of 1.2 mm.

[0061] No defects such as edge cracking or particle detachment occurred in the sheet during the processing. The prepared magnesium-lithium material ultrathin sheet has good forming performance and high strength and high modulus mechanical properties, as shown in Table 1.

[0062] Comparative Example 1 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 1, and the steps are basically the same as those in Example 1. The difference lies in... Instead of performing the ball milling process in step S11 to prepare preforms, the reinforcing particles TiB2 and Al powder were directly added to a vacuum electromagnetic induction furnace along with other raw materials for vacuum melting in step S12.

[0063] Severe particle agglomeration occurred in the prepared magnesium-lithium material ultrathin plate, and the mechanical properties are shown in Table 1.

[0064] Comparative Example 2 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formulation is the same as that of magnesium-lithium materials in Example 1, but the D50 of the reinforcing particles TiB2 is 100 μm.

[0065] The steps are the same as in Example 1.

[0066] During multi-pass rolling, excessively large particle diameters lead to localized stress concentration and cracks at the particle interface, making it impossible to prepare ultra-thin plates normally.

[0067] Comparative Example 3 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 1, and the steps are basically the same as those in Example 1. The difference lies in... Without performing the homogenization process in step S2, the ingot is directly subjected to the free forging process in step S3 and the multi-pass rolling process in step S4.

[0068] Due to the lack of homogenization heat treatment, the softening precipitate phase near the interface was not generated during the free forging and multi-pass rolling stages. The stress concentration near the magnesium-lithium material particles was obvious, and cracks were generated during the deformation process, making it impossible to prepare ultra-thin plates normally.

[0069] Comparative Example 4 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 2, and the steps are basically the same as those in Example 2. The difference lies in... The deformation temperature during the free forging process in step S3 is room temperature (25~30℃).

[0070] Due to the excessively low deformation temperature, the forging billet cracked, making it impossible to prepare ultra-thin plates normally.

[0071] Comparative Example 5 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 2, and the steps are basically the same as those in Example 2. The difference lies in... The amount of plastic deformation during the free forging process in step S3 is 20%.

[0072] Due to the insufficient free forging deformation, the deformation during multi-pass rolling was excessive, resulting in a noticeable texture, poor plasticity, and significant anisotropy in the prepared magnesium-lithium material ultrathin sheet. The mechanical properties are shown in Table 1.

[0073] Comparative Example 6 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 3, and the steps are basically the same as those in Example 3. The difference lies in... Intermediate annealing was not performed during the multi-pass rolling process in step S4.

[0074] Because intermediate annealing was not performed, the internal stress of the substrate was too high during the multi-pass rolling process, which led to particle desorption and edge cracking during the rolling process, making it impossible to prepare ultra-thin plates normally.

[0075] Comparative Example 7 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 3, and the steps are basically the same as those in Example 3. The difference lies in... In step S4, the rolling temperature during the multi-pass rolling process is room temperature (25~30℃).

[0076] Due to excessively low rolling temperature, the internal stress of the substrate was too high, resulting in edge cracking defects and making it impossible to prepare ultra-thin plates normally.

[0077] Comparative Example 8 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 3, and the steps are basically the same as those in Example 3. The difference lies in... The intermediate annealing temperature for the multi-pass rolling process in step S4 is 450℃.

[0078] The excessively high annealing temperature caused abnormal growth of the basic grains after recrystallization, resulting in low strength.

[0079] Comparative Example 9 This comparative example provides a forging and rolling composite preparation method for ultrathin magnesium-lithium materials. The raw material formula is the same as that of the magnesium-lithium materials in Example 3, and the steps are basically the same as those in Example 3. The difference lies in... In step S4, the reduction per pass in the multi-pass rolling process is 40%.

[0080] Due to excessive reduction per pass during multi-pass rolling, edge cracks occur in the rolled sheet, making it impossible to prepare ultra-thin sheets normally.

[0081] Performance testing: The mechanical properties of the magnesium-lithium materials prepared in each embodiment and comparative example were tested. The tensile properties (yield strength, tensile strength, and elongation) were tested according to the national standard GB / T228.1-2010, and the elastic modulus was tested according to the national standard GB / T22315-2008. The test results are shown in Table 1.

[0082] Table 1

[0083] In summary, this invention achieves a uniform and dispersed distribution of reinforcing particles in a magnesium-lithium alloy matrix under high particle content conditions through a composite processing technology combining ball milling pretreatment, vacuum stirring casting, homogenization treatment, free forging, and multi-pass rolling. This process simultaneously suppresses particle agglomeration and weak interfacial bonding. The free forging stage significantly breaks down the coarse as-cast microstructure and particle aggregation regions, providing a uniform and refined matrix structure for subsequent stable rolling. During multi-pass low-reduction rolling, the matrix material undergoes recrystallization and softening, resulting in a favorable dislocation storage structure and stress coordination zone within the composite material. Ultimately, a high-strength, high-modulus ultrathin magnesium-lithium alloy sheet with excellent forming quality is successfully obtained.

[0084] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A magnesium-lithium ultrathin plate material, characterized in that, The composition by mass percentage is Li: 1~15%, Al: 0.5~6%, Zn: 0.5~6%, RE: 0.1~3%, reinforcing particles: 4~20%, with the balance being Mg and unavoidable impurities.

2. The magnesium-lithium ultrathin plate material according to claim 1, characterized in that, The RE is one or more of Y, Gd, Er, Nd, and Yb.

3. The magnesium-lithium ultrathin plate material according to claim 1, characterized in that, The reinforcing particles are one or more of TiB2, SiC, and B4C; And / or, the reinforcement particle D50 is 1~10μm.

4. The magnesium-lithium ultrathin plate material according to claim 1, characterized in that, The thickness of the magnesium-lithium material ultrathin plate is 0.5~1.5mm.

5. The magnesium-lithium ultrathin plate material according to claim 1, characterized in that, The ultrathin magnesium-lithium material has an elastic modulus of 50~78GPa, a yield strength of 364~385MPa, a tensile strength of 405~426MPa, and an elongation of 6~12%.

6. The forging and rolling composite preparation method of magnesium-lithium material ultrathin plate material according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. The reinforcing particles and Al powder are ball-milled to obtain composite powder, which is then cold-pressed to obtain preforms. The preforms are then added to the vacuum molten liquid of other raw materials, kept warm and mechanically stirred until the preforms are completely melted, and then cast to obtain ingots. S2. The ingot is homogenized to obtain a homogenized billet; S3. The homogenized billet is subjected to free forging to obtain a medium-thick plate. S4. The medium-thick plate is subjected to multiple rolling processes, and intermediate annealing is performed between the multiple processes to obtain the magnesium-lithium material ultrathin plate.

7. The forging-rolling composite preparation method according to claim 6, characterized in that, In step S1, the parameters of the ball mill are: rotation speed 200~400 rpm, time 4~10 h; And / or, in step S1, the parameters of the cold pressing are: pressure 15~20MPa, time 15~30min; And / or, in step S1, all raw materials except Al and reinforcing materials are heated to 660~700°C for vacuum melting to obtain the vacuum melt liquid; And / or, in step S1, after the preform is completely melted, the temperature is adjusted to 700~750℃ for casting.

8. The forging-rolling composite preparation method according to claim 6, characterized in that, In step S2, the homogenization processing parameters are: temperature 300~400℃ and time 2~5h.

9. The forging-rolling composite preparation method according to claim 6, characterized in that, In step S3, the parameters for free forging are: deformation temperature 200~350℃, and plastic deformation amount not less than 60%.

10. The forging-rolling composite preparation method according to claim 6, characterized in that, In step S4, the parameters for the multi-pass rolling are: rolling temperature 150~200℃, and rolling reduction rate per pass 5%~10%; And / or, in step S4, when the deformation reaches 50%~60% and 80%~90% in the multi-pass rolling, intermediate annealing is performed respectively, with an annealing temperature of 250~300℃ and an annealing time of 0.5~1h.

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