CN119456676A

CN119456676A - A method for preparing high-strength ultra-thin lightweight Al/Mg-Li/Al composite foil

Info

Publication number: CN119456676A
Application number: CN202510058830.8A
Authority: CN
Inventors: 李传强; 林宏辉; 江舒佳; 熊广鑫
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2025-01-15
Filing date: 2025-01-15
Publication date: 2025-02-18

Abstract

The invention belongs to the field of alloy materials, and particularly relates to a preparation method of a high-strength ultrathin light Al/Mg-Li/Al composite foil, which comprises the steps of firstly cutting magnesium-lithium alloy and a pure aluminum plate into blocks with equal length and width and different thickness, stacking the blocks in a mode of Al/Mg-Li/Al after cleaning, rolling the blocks into a composite plate through large deformation at a certain temperature, and then repeatedly cold-rolling the composite plate with large deformation and small deformation and performing pressure finish cold rolling. The method has low manufacturing cost and simple and convenient method, greatly improves the strength, and is easy to realize large-scale batch production.

Description

Preparation method of high-strength ultrathin light Al/Mg-Li/Al composite foil

Technical Field

The invention belongs to the field of alloy materials, and particularly relates to a preparation method of a high-strength ultrathin light Al/Mg-Li/Al composite foil.

Background

The magnesium-lithium alloy is used as the lightest metal structural material, has high specific strength, high specific rigidity, excellent damping characteristic and the like, and has wide application prospect in the fields of aerospace, electronic products, medical appliances, automobiles and the like. However, the strength, elastic modulus, corrosion resistance, etc. of magnesium lithium alloys severely restrict their industrial applications. Aluminum and aluminum alloy have the advantages of low density, strong corrosion resistance, good impact absorbability, good processing formability and the like, and have wide application in the fields of food industry, chemical industry, aerospace, automobile industry and the like. Aluminum element is often added in the alloying treatment of the magnesium-lithium alloy, so that the strength and corrosion resistance of the magnesium-lithium alloy can be improved, and the microstructure and mechanical property of the magnesium alloy material can be effectively improved by plastic deformation. Therefore, a layer of aluminum with good corrosion resistance is coated on the surface of the magnesium-lithium alloy by using the laminating technology to form a sandwich-type layered material, so that the magnesium-lithium alloy can be protected from corrosion and the strength of the magnesium-lithium alloy can be improved, and a novel excellent Al/Mg-Li/Al composite material is prepared. On the other hand, with conventional magnesium alloys, plastic deformation is difficult at room temperature due to its close-packed hexagonal structure (HCP) characteristics, and it is impossible to form magnesium alloy foils at room temperature. The addition of lithium element can significantly improve the plasticity of magnesium alloys, especially when the lithium element content exceeds 10.3 wt%, the crystal structure of magnesium alloys will be totally transformed into Body Centered Cubic (BCC) structure, which greatly improves the room temperature ductility thereof. Because the magnesium-lithium alloy with high lithium content and the pure aluminum material both have high plastic deformation capability and strong coordinated deformation capability, the two materials are subjected to pad rolling, and the foil is prepared by adopting a room-temperature rolling technology, and meanwhile, the mechanical properties of the Al/Mg-Li/Al composite foil are improved due to the introduction of large plastic deformation (accumulated pad rolling) and Mg/Al composite heterostructures.

The magnesium alloy foil is a thin plate strip, the existing preparation process is difficult to realize large-scale production, and the cost is high. In recent years, many researchers develop a series of foil preparation technologies for magnesium-lithium alloy, such as a rolling preparation method for magnesium or magnesium alloy foil disclosed in CN200910307937.2, a rolling method for magnesium alloy sheet material coil/foil and a roller system thereof disclosed in CN201210100705.1, and a rolling preparation method for magnesium or magnesium alloy foil by wrapping an aluminum plate into a rolled package, cutting out wrapping edges after rolling and separating the foil, but all the patents need hot rolling or annealing to ensure rolling quality, have complicated processing procedures and high cost, are only single magnesium or magnesium alloy foil, and have not reported and disclosed related Al/Mg-Li/Al laminated composite foil preparation technologies.

Disclosure of Invention

In order to solve the problems that in the prior art, the preparation cost of the magnesium alloy foil is high and the preparation of the Al/Mg-Li/Al laminated composite foil is still blank, the invention mainly provides a high-strength ultrathin light Al/Mg-Li/Al composite foil, and a preparation technology and a processing scheme of the foil:

the preparation method of the high-strength ultrathin light Al/Mg-Li/Al composite foil comprises the following steps:

a, cutting magnesium-lithium alloy and aluminum into blocks to obtain magnesium-lithium alloy plates and aluminum plates;

b, placing a clean magnesium-lithium alloy plate in the middle, respectively placing a clean aluminum plate on the upper surface and the lower surface of the magnesium-lithium alloy plate for stacking, and fixing and binding by using aluminum wires to obtain an Al/Mg-Li/Al stacked plate;

C, preheating the Al/Mg-Li/Al stacked plate for 5-10 min at 300-450 ℃ in the atmosphere of inert gas, taking out and rapidly rolling at 40-60% rolling reduction to obtain an Al/Mg-Li/Al composite plate;

d, performing multi-pass cold rolling on the Al/Mg-Li/Al composite plate with small deformation amount, the rolling reduction of which is 2-30%, to a thickness of 0.5-1 mm, and performing multi-pass cold rolling on the Al/Mg-Li/Al composite plate with large deformation amount, the rolling reduction of which is 30-50%, to a target thickness.

Further, the Al/Mg-Li/Al composite foil after cold rolling is finished, so that the problems of wavy edges, coiled material cracks and central concave-convex are solved, and the thickness tolerance is less than +/-0.005.

Further, the length and width of the magnesium-lithium alloy plate in the step a are the same as those of the aluminum plate.

Further, the small deformation multi-pass cold rolling in the step d means that the rolling reduction before the thickness of the plate is reduced to 1-3 mm is 2-10%, the plate is prevented from cracking due to the fact that the rolling reduction is excessive, the rolling reduction of all subsequent passes is 10-30%, and the thickness of the plate is rolled to be not less than 0.5mm.

Further, the large deformation multi-pass cold rolling in the step d means that the reduction of the first three passes is 30-40%, and the reduction of the subsequent passes is 40-50% until the thickness of the Al/Mg-Li/Al foil is rolled to the target thickness.

And d, performing cold rolling for multiple times with large deformation, and continuously performing repeated cold rolling until the thickness of the foil is rolled to the target thickness after the thickness is 0.1-0.05 mm.

Further, the rolling force for continuing the repeated cold rolling is 0.05-0.01 ton/mm ².

Further, before stacking the magnesium-lithium alloy plate and the aluminum plate, carrying out surface treatment on the magnesium-lithium alloy plate and the aluminum plate, wherein the surface treatment comprises the following steps of cleaning the magnesium-lithium alloy plate with dilute nitric acid, cleaning the aluminum plate with a mixed solution of dilute hydrochloric acid and hydrofluoric acid, polishing the surface of the plate to remove an oxide film, cleaning the surface of the plate with acetone to remove grease on the surface of the plate, washing the surface with ethanol to remove surface impurities, drying the plate, and finally polishing the surface of the alloy to expose fresh metal, thereby obtaining the clean magnesium-lithium alloy plate and the aluminum plate.

The high-strength ultrathin light Al/Mg-Li/Al composite foil prepared by the method has the advantages that the middle layer is made of magnesium-lithium alloy, and the surface layer is made of aluminum.

Further, the thickness is 0.02-0.1 mm, wherein the thickness ratio of the aluminum on the surface layer to the magnesium-lithium alloy on the middle layer is 0.01-1:1.

Further, the magnesium-lithium alloy has a body-centered cubic structure, and comprises 10.3-20 wt.% of lithium, 0.01-20 wt.% of zinc, the total amount of unavoidable impurities is less than 0.03%, and the balance of magnesium. The aluminum plate comprises 99.7-99.8 wt.% of aluminum, and the total amount of unavoidable impurities is less than 0.03%.

By adopting the scheme, the method has the following advantages:

According to the invention, the Al/Mg-Li/Al composite plate is obtained by rolling with the rolling reduction of 40-60%, then cold rolling is carried out for a plurality of times at room temperature, the preparation of the Al/Mg-Li/Al composite foil is realized by adopting fewer steps, the rolling process is simple, the cost is low, and the large-scale batch production is easy to realize.

The method of the invention realizes large accumulated cold rolling deformation, improves the dimensional accuracy of the foil, and the thickness deviation can reach +/-0.002 mm.

The processing process of the invention is only carried out at 300-450 ℃ for the initial composite board, and the rest is carried out at room temperature, thereby solving the problem that the surface of the foil is easy to oxidize in the annealing process in the magnesium alloy cold rolling process in the prior art, and the obtained foil has high surface smoothness.

The invention firstly carries out heat preservation treatment under the atmosphere of protective gas, rapidly rolls the plates to be rolled into the composite plate, greatly reduces surface oxidation, is easier to combine between interfaces of the composite plate, and provides a good foundation for rolling the composite plate into a foil.

The finish rolling Al/Mg-Li/Al composite foil with good flatness and less burrs can be obtained after multi-pass room temperature cold rolling, and the energy consumption and the yield are low. The invention can realize the preparation of the ultrathin foil by using a small-tonnage multi-roller mill or a single-roller mill, and the preparation of the foil has lower requirements on equipment.

The foil combines the advantages of the magnesium-lithium alloy and the aluminum alloy, and the strength is greatly improved. The tensile strength of the foil with the thickness of 0.02mm reaches 375 MPa, the thickness deviation is +/-0.002 mm, the flatness is good, and burrs are few.

Drawings

FIG. 1 is a photograph of an initial Al/Mg-Li/Al composite foil.

FIG. 2 is a photograph of a 0.1mm thick Al/Mg-Li/Al composite foil.

FIG. 3 is a photograph of a 0.05 mm thick Al/Mg-Li/Al composite foil.

FIG. 4 is a photograph of a 0.02mm thick Al/Mg-Li/Al composite sheet.

FIG. 5 is a photograph of the thickness of a 0.02mm thick Al/Mg-Li/Al composite foil.

FIG. 6 is a photograph of microstructure of 0.02mm thick Al/Mg-Li/Al composite foil.

FIG. 7 is a graph of the room temperature engineering stress strain for Al/Mg-Li/Al composite plates/foils of different thickness specifications.

Detailed Description

The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Taking 1060 pure aluminum plate with the purity of 99.7-99.8 wt.% of magnesium-lithium alloy and aluminum, wherein the magnesium-lithium alloy comprises, by mass, 11% of Li and 6% of Zn, the total amount of unavoidable Fe, cu, ni, mn, si impurities is less than 0.03%, and the balance of Mg;

(2) And (3) processing magnesium-lithium alloy and pure aluminum raw materials to be rolled in a stacking mode:

Cutting a magnesium-lithium alloy cast ingot to be accumulated and rolled and a 1060 pure aluminum plate into blocks with the same growth width and different thickness (the thickness of the magnesium-lithium alloy is larger than that of the pure aluminum), carrying out surface treatment, cleaning the magnesium-lithium alloy plate by dilute nitric acid, cleaning the 1060 pure aluminum plate by mixed solution of dilute hydrochloric acid and hydrofluoric acid, polishing the surface of the plate by abrasive paper to remove an oxide film, cleaning by acetone to remove grease on the surface of the plate, washing by absolute ethyl alcohol to remove surface impurities, drying by an electric blower, polishing the surface of the alloy by a steel wire brush to expose fresh metal, stacking the magnesium-lithium alloy plate obtained in the step b and the aluminum alloy plate in an Al/Mg-Li/Al mode, and fixing and binding by a thin aluminum wire (with the diameter of 0.1 mm);

(3) Preparation of Al/Mg-Li/Al composite plate:

Preheating the Al/Mg-Li/Al stacked plate obtained in the steps at 400 ℃ under the protection of argon for 10min, taking out, and rapidly rolling at a reduction of 50% to obtain an initial Al/Mg-Li/Al composite plate;

FIG. 1 is an initial Al/Mg-Li/Al composite sheet material obtained in step (3). As can be seen from the figure, the magnesium-lithium alloy and the pure aluminum sheets of the upper layer and the lower layer are tightly combined.

(4) Cold rolling with small deformation and then cold rolling with large deformation:

And (3) performing multi-pass cold rolling on the initial Al/Mg-Li/Al composite plate with the reduction of 2-30% at room temperature by using a small-tonnage single-roller/multi-roller mill. Wherein the reduction before the thickness of the plate is reduced to 3 mm is 2-10%, the plate is prevented from cracking due to excessive reduction, and the reduction of all the later passes is 10-30%, until the thickness of the plate is reduced to 0.5-mm. And then carrying out multi-pass cold rolling on the composite plate with the thickness of 0.5mm and the reduction of 30% -50%, wherein the reduction of the first three passes is 30% -40%, the reduction of all the later passes is 40% -50%, and the thickness of the composite plate is reduced to 0.1 mm.

FIG. 2 shows the Al/Mg-Li/Al composite foil with the thickness of 0.1 mm, and the surface of the obtained foil is smooth, the aluminum layer and the alloy layer are not separated, and the layers are tightly combined to form a complete whole.

Example 2 differs from example 1 in that:

at room temperature, a small-tonnage single-roll/multi-roll mill is used for carrying out multi-pass cold rolling on an initial blank with the thickness of 5mm and the reduction of 2-30 percent. Wherein the reduction of the sheet material is 2-10% before the thickness of the sheet material is reduced to 3 mm, the sheet material is prevented from cracking due to the excessive reduction, and the reduction of the sheet material in all the later passes is 10-30% until the thickness of the sheet material is reduced to 0.5-mm. And then carrying out multi-pass cold rolling on the composite plate with the thickness of 0.5 mm and the reduction of 30% -50%, wherein the reduction of the first three passes is 30% -40%, the reduction of all the later passes is 40% -50%, and the thickness of the composite plate is reduced to 0.05 mm.

FIG. 3 shows the Al/Mg-Li/Al composite foil with the thickness of 0.05 mm, and the obtained foil has smooth surface, no separation between the aluminum layer and the alloy layer, good interface bonding between the layers and no obvious flaws.

Example 3 differs from example 1 in that:

At room temperature, a small-tonnage single-roll/multi-roll mill is used for carrying out multi-pass cold rolling on an initial blank with the thickness of 5mm and the reduction of 2-30 percent. Wherein the reduction of the sheet material is 2-10% before the thickness of the sheet material is reduced to 3 mm, the sheet material is prevented from cracking due to the excessive reduction, and the reduction of the sheet material in all the later passes is 10-30% until the thickness of the sheet material is reduced to 0.5-mm. Then carrying out multi-pass cold rolling on the composite plate with the thickness of 0.5 mm and the rolling reduction of 30% -50%, wherein the rolling reduction of the first three passes is 30% -40%, the rolling reduction of all the later passes is 40% -50%, and the thickness of the composite plate is reduced to 0.05 mm;

(5) At room temperature, increasing the rolling force between two rollers of a small-tonnage single-roller/multi-roller rolling mill to 0.01-0.05 ton/mm ², and repeatedly cold-rolling the Al/Mg-Li/Al composite foil until the thickness of the foil is rolled to 0.02 mm;

(6) Finishing the finish rolled Al/Mg-Li/Al composite foil, thoroughly solving the problems of wavy edges, coiled material cracks and central concave-convex, and enabling the thickness tolerance to be less than +/-0.002.

FIGS. 4 and 5 show the resulting Al/Mg-Li/Al composite foil having a thickness of 0.02 mm. As can be seen from the figure, the obtained foil has a flat and smooth surface and no obvious flaws.

The microstructure photograph of fig. 6 shows that the outermost aluminum well encapsulates the internal magnesium-lithium alloy material, the Al/Mg interface bonding is good, and no obvious defects exist.

Comparative example 1 the difference from example 1 is that:

And (3) performing multi-pass cold rolling on the initial Al/Mg-Li/Al composite plate with the reduction of 2-30% at room temperature by using a small-tonnage single-roller/multi-roller mill. Wherein the reduction of the plate thickness is 2-10% before the reduction of the plate thickness to 3mm, the plate is prevented from cracking due to the excessive reduction, and the reduction of the plate thickness in all the later passes is 10-30% until the plate thickness is reduced to 2 mm.

Comparative example 2 differs from example 1 in that:

And (3) performing multi-pass cold rolling on the initial Al/Mg-Li/Al composite plate with the reduction of 2-30% at room temperature by using a small-tonnage single-roller/multi-roller mill. Wherein the reduction of the thickness of the plate is 2-10% before the reduction of the thickness of the plate to 3 mm, the plate is prevented from cracking due to the excessive reduction, and the reduction of the thickness of the plate in all the later passes is 10-30% until the thickness of the plate is reduced to 1mm.

Comparative example 3 differs from example 1 in that:

And (3) performing multi-pass cold rolling on the initial Al/Mg-Li/Al composite plate with the reduction of 2-30% at room temperature by using a small-tonnage single-roller/multi-roller mill. Wherein the reduction before the thickness of the plate is reduced to 3mm is 2-10%, the plate is prevented from cracking due to excessive reduction, and the reduction of all the later passes is 10-30%, until the thickness of the plate is reduced to 0.5-mm.

Examples sample testing:

The tensile strength of each example and comparative example was tested, and engineering stress strain curves were plotted, as shown in fig. 7, and it can be seen from the graph that the tensile strength of Al/Mg-Li/Al composite plate/foil increases with decreasing thickness, wherein the tensile strength of 0.02 mm gauge foil reaches 375: 375 MPa.

It will be apparent to those skilled in the art from this disclosure that various other changes and modifications can be made which are within the scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a high-strength ultra-thin lightweight Al/Mg-Li/Al composite foil, characterized in that it comprises the following steps:

a. Cutting the magnesium-lithium alloy and aluminum into blocks to obtain magnesium-lithium alloy plates and aluminum plates;

b. Place a clean magnesium-lithium alloy plate in the middle, place clean aluminum plates on the upper and lower surfaces of the magnesium-lithium alloy plate, and stack them, and fix and tie them with aluminum wire to obtain an Al/Mg-Li/Al stacked plate;

c. In an inert gas atmosphere, preheat the Al/Mg-Li/Al stacked sheet at 300-450°C for 5-10 min, take it out and quickly roll it at a reduction of 40-60% to obtain an Al/Mg-Li/Al composite sheet;

d. At room temperature, the Al/Mg-Li/Al composite sheet is subjected to multiple cold rolling with a small deformation amount of 2-30% reduction to a thickness of 0.5-1 mm; then, the Al/Mg-Li/Al composite sheet is subjected to multiple cold rolling with a large deformation amount of 30-50% reduction to a target thickness.

2. The method for preparing a high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 1 is characterized in that the magnesium-lithium alloy plate in step a has the same length and width as the aluminum plate.

3. The method for preparing a high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 1 is characterized in that the small deformation multi-pass cold rolling in step d means that the reduction before the plate thickness is reduced to 1-3 mm is 2-10%, and the reduction in all subsequent passes is 10-30% until the plate thickness is rolled to not less than 0.5 mm.

4. The method for preparing a high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 1 is characterized in that the large deformation multi-pass cold rolling in step d means that the reduction in the first three passes is 30-40%, and the reduction in the subsequent passes is 40-50%, until the thickness of the Al/Mg-Li/Al foil is rolled to the target thickness.

5. The method for preparing a high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 1 is characterized in that in step d, multiple cold rolling passes are performed with a large deformation amount, and after the thickness is rolled to 0.1-0.05 mm, repeated cold rolling is continued until the foil thickness is rolled to a target thickness.

6 . The method for preparing a high-strength ultra-thin lightweight Al/Mg-Li/Al composite foil according to claim 5 , wherein the rolling force for the repeated cold rolling is 0.05-0.01 ton/mm ² .

7. The method for preparing a high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 1 is characterized in that, before stacking the magnesium-lithium alloy plate and the aluminum plate, the magnesium-lithium alloy plate and the aluminum plate are surface treated, comprising the following steps: cleaning the magnesium-lithium alloy plate with dilute nitric acid, cleaning the aluminum plate with a mixed solution of dilute hydrochloric acid and hydrofluoric acid, then grinding the plate surface to remove the oxide film, then washing with acetone to remove grease on the plate surface, rinsing with ethanol to remove surface impurities, then drying, and finally grinding the alloy surface to expose fresh metal to obtain a clean magnesium-lithium alloy plate and aluminum plate.

8. A high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil prepared by the method according to any one of claims 1 to 7, characterized in that the middle layer is a magnesium-lithium alloy and the surface layer is aluminum.

9. The high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 8 is characterized in that the thickness is 0.02-0.5 mm; wherein the thickness ratio of the aluminum in the surface layer to the magnesium-lithium alloy in the middle layer is 0.01-1:1.

10. The high-strength, ultra-thin and lightweight Al/Mg-Li/Al composite foil according to claim 8, characterized in that the magnesium-lithium alloy has a body-centered cubic structure; the magnesium-lithium alloy comprises 10.3-20wt.% lithium, 0.01-20wt.% zinc, and the balance is magnesium.