Hydrogen embrittlement resistant aluminum lithium alloy and preparation method thereof

Abstract

The invention discloses a hydrogen embrittlement-resistant aluminum-lithium alloy and a preparation method thereof. In order to improve the hydrogen embrittlement resistance of the aluminum-lithium alloy, the element Li is injected into the two faces of the thin-plate-shaped aluminum alloy through vacuum ion injection treatment, then all the elements are fully diffused in a vacuum annealing mode, brittle Li H and Li3A1 H6 phases formed during smelting in the prior art are avoided, and then the aluminum-lithium alloy with the excellent hydrogen embrittlement resistance is obtained. In addition, the metal Hf is added into the aluminum-lithium alloy, so that the ductility of the aluminum-lithium alloy can be effectively improved. Researches show that with the increase of the content of the Hf element, the elongation of the aluminum-lithium alloy is in a trend of increasing first and then decreasing. And on the basis of metal aluminum, when the proportion of Hf is 0.9 wt%-3.5 wt%, the ductility of the alloy material is higher than 10%.

Description

Technical Field

[0001] The invention relates to the field of aluminum-lithium alloys (C22C21 / 00), and in particular to an aluminum-lithium alloy resistant to hydrogen embrittlement and a preparation method thereof. Background Art

[0002] Aluminum-lithium alloys have high specific strength, specific stiffness, and excellent corrosion resistance and fatigue resistance, and have attracted much attention in many key fields such as aviation, aerospace, and navigation. Since Li is active in nature and easily reacts with moisture in the air, hydrogen will dissolve in large quantities in the aluminum-lithium alloy during the smelting process, forming brittleness after solidification, leading to the occurrence of "hydrogen embrittlement". On the other hand, in some fields with high requirements for plasticity, aluminum-lithium alloys are required to have good elongation. Based on this, it is necessary to design an aluminum-lithium alloy that is resistant to hydrogen embrittlement and has excellent elongation. Summary of the invention

[0003] The object of the present invention is to provide an aluminum-lithium alloy having hydrogen embrittlement resistance and excellent elongation and a preparation method thereof.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing an aluminum-lithium alloy resistant to hydrogen embrittlement, the preparation method comprising the following steps:

[0006] 100 parts by weight of Al, 2.6-3.1 parts by weight of Cu, 0.9-1.1 parts by weight of Mg, 0.4-0.8 parts by weight of Zr, 0.5-0.9 parts by weight of Sr, 0.2-0.5 parts by weight of Ti and 0.9-3.5 parts by weight of Hf are put into a vacuum resistance furnace, heated and melted, and then kept warm for 5-8 hours, and electromagnetic stirring is performed at a speed of 450-500 r / min during the heat preservation process; after filtering and casting, annealing is performed at 420-450° C. for 8-10 hours, and then placed in a vacuum resistance furnace for solution treatment for 24-28 hours, and naturally aged for 60-72 hours, and after processing, an aluminum alloy blank with a thickness of 2-3 mm is obtained;

[0007] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120-150 keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 4×10 12 -6×10 12 ions / cm 2 ;

[0008] The aluminum alloy after Li ion implantation is placed in a vacuum annealing furnace, heat treated at 350-380° C. for 12-15 hours, and then naturally cooled to obtain an aluminum-lithium alloy.

[0009] Preferably, the thickness of the aluminum alloy blank is 2 mm.

[0010] Preferably, the solution treatment time is 24 hours.

[0011] Preferably, the natural aging time is 60 hours.

[0012] Preferably, the heat treatment time is 12 hours.

[0013] Preferably, the heat treatment temperature is 350°C.

[0014] Furthermore, the present invention also provides an aluminum-lithium alloy resistant to hydrogen embrittlement, and the aluminum-lithium alloy resistant to hydrogen embrittlement is prepared by the above method.

[0015] In order to improve the hydrogen embrittlement resistance of aluminum-lithium alloy, the present invention injects the element Li into both sides of the thin plate-shaped aluminum alloy through vacuum ion implantation treatment, and then fully diffuses the elements through vacuum annealing, thereby avoiding the brittle LiH and Li3Al H6 phases formed during smelting in the prior art, and thus obtaining an aluminum-lithium alloy with excellent hydrogen embrittlement resistance.

[0016] In addition, the present invention can effectively improve the elongation of the aluminum-lithium alloy by adding metal Hf. Studies have shown that as the content of Hf increases, the elongation of the aluminum-lithium alloy shows a trend of first increasing and then decreasing. Taking metal aluminum as the benchmark, when the proportion of Hf is 0.9wt%-3.5wt%, the elongation of the alloy material is higher than 10%. DETAILED DESCRIPTION

[0017] The technical effects of the present invention are verified below through specific examples, but the embodiments of the present invention are not limited thereto.

[0018] Example 1

[0019] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr, 0.2 parts by weight of Ti and 0.9 parts by weight of Hf were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0020] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm2 ;

[0021] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0022] Example 2

[0023] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr, 0.2 parts by weight of Ti and 1.5 parts by weight of Hf were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0024] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm 2 ;

[0025] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0026] Example 3

[0027] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr, 0.2 parts by weight of Ti and 2.1 parts by weight of Hf were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0028] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm 2 ;

[0029] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0030] Example 4

[0031] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr, 0.2 parts by weight of Ti and 2.8 parts by weight of Hf were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0032] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm 2 ;

[0033] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0034] Example 5

[0035] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr, 0.2 parts by weight of Ti and 3.5 parts by weight of Hf were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0036] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm 2 ;

[0037] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0038] Comparative Example 1

[0039] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr and 0.2 parts by weight of Ti were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0040] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm 2 ;

[0041] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0042] Comparative Example 2

[0043] 100 parts by weight of Al, 2.6 parts by weight of Cu, 0.9 parts by weight of Mg, 0.4 parts by weight of Zr, 0.5 parts by weight of Sr, 0.2 parts by weight of Ti and 8.0 parts by weight of Hf were put into a vacuum resistance furnace, heated and melted, and then kept warm for 5 hours, and electromagnetic stirring was performed at a speed of 450 r / min during the heat preservation process; after filtration and casting, annealing was performed at 420° C. for 8 hours, and then placed in a vacuum resistance furnace for solution treatment for 24 hours, and naturally aged for 60 hours, and after processing, an aluminum alloy blank with a thickness of 2 mm was obtained;

[0044] Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 -4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 6×10 12 ions / cm 2 ;

[0045] The aluminum alloy after Li ion implantation was placed in a vacuum annealing furnace, heat treated at 380° C. for 12 h, and naturally cooled to obtain an aluminum-lithium alloy.

[0046] Next, we evaluated the elongation of the aluminum-lithium alloy in Examples 1-5 and Comparative Examples 1-2. The experimental results are shown in Table 1.

[0047] Table 1 Elongation of each sample

[0048] serial number Elongation / % Example 1 10.5 Example 2 12.1 Example 3 13.6 Example 4 15.0 Example 5 13.9 Comparative Example 1 7.3 Comparative Example 2 9.3

[0049] As can be seen from Table 1, adding metal Hf to the aluminum-lithium alloy can effectively improve its elongation. As the Hf element content increases, the elongation of the aluminum-lithium alloy shows a trend of first increasing and then decreasing. Taking metal aluminum as the benchmark, when the proportion of Hf is 0.9wt%-3.5wt%, the elongation of the alloy material is higher than 10%.

[0050] 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 technical 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 method for preparing an aluminum-lithium alloy resistant to hydrogen embrittlement, characterized in that: The preparation method comprises the following steps: 100 parts by weight of Al, 2.6-3.1 parts by weight of Cu, 0.9-1.1 parts by weight of Mg, 0.4-0.8 parts by weight of Zr, 0.5-0.9 parts by weight of Sr, 0.2-0.5 parts by weight of Ti and 0.9-3.5 parts by weight of Hf are put into a vacuum resistance furnace, heated and melted, and then kept warm for 5-8 hours, and electromagnetic stirring is performed at a speed of 450-500 r / min during the heat preservation process; after filtering and casting, annealing is performed at 420-450° C. for 8-10 hours, and then placed in a vacuum resistance furnace for solution treatment for 24-28 hours, and naturally aged for 60-72 hours, and after processing, an aluminum alloy blank with a thickness of 2-3 mm is obtained; Place the aluminum alloy blank into the metal ion implantation equipment and adjust the vacuum degree of the ion implantation equipment chamber to 1×10 - 4 Pa, metallic lithium was used to perform ion implantation on both sides of the aluminum alloy blank, the ion voltage was 120-150 keV, and the Li ion implantation amount on one side of the aluminum alloy blank was 4×10 12 -6×10 12 ions / cm 2 ; The aluminum alloy after Li ion implantation is placed in a vacuum annealing furnace, heat treated at 350-380° C. for 12-15 hours, and then naturally cooled to obtain an aluminum-lithium alloy.

2. A preparation method according to claim 1, characterized in that: The thickness of the aluminum alloy blank is 2 mm.

3. A preparation method according to claim 1, characterized in that: The solution treatment time is 24h.

4. A preparation method according to claim 1, characterized in that: The natural aging time is 60h.

5. A preparation method according to claim 1, characterized in that: The heat treatment time is 12h.

6. A preparation method according to claim 1, characterized in that: The heat treatment temperature is 350°C.

7. A hydrogen embrittlement resistant aluminum-lithium alloy, characterized in that: The hydrogen embrittlement-resistant aluminum-lithium alloy is prepared by the method according to any one of claims 1 to 6.