Study On The Preparation Process And Performance Of 8090 Al-Li Alloy

Aluminum lithium alloy is a kind of aluminum material, it has low density, and high strength, high stiffness, and high modulus features, compared with aluminum alloy, it can make structure quality reduce by 10%-20%, stiffness improve by almost 20%, so aluminum lithium alloy as structure material has a great of potential economic effects, it is publicly conceived as the most potential structure material in 21st.The development of aluminum-lithium alloys can be divided into three stages. First-generation aluminum-lithium alloy was developed in the 1950 of the 20th century, the typical brand of United States by 2020, Russia 1420, but there is the issues such as difference of anisotropy and fracture toughness. The second generation of Al-Li alloy was developed in the 1980 of the 20th century, the typical Al-Li alloys are 2090 and 8090. These alloys are notable and high modulus, but remain being with strong anisotropy of mechanical properties. In order to solve the weakness of the second generation, the third generation of lithium aluminum alloy is made in the 1990 s,2094 and 2095 are the typical brands, in recent years Al-Li alloy began to develope forward the direction of super toughness, low density, low anisotropy, better welding performance and thermal stability, etc.This topic mainly about 8090 aluminum-lithium alloy melting technology, and the influence of heat treatment on the properties of materials. Because of lithium with very high chemical activity, easily react violently with water, during aluminum-lithium alloy melting process light elements seriously loss, or even cause an explosion. Slag is prone to segregation of ingot, aluminum-lithium alloy smelting process is complicated, this study used conventional smelting method of smelting 8090 aluminum-lithium alloy, and explores the coverage on the chemical composition, as well as the effects of lithium on segregation of ingot. And subsequent heat treatment is used to improve the alloy's microstructure and properties. The results show that adding covering agent can reduce the loss of lithium and magnesium, lithium slight deviation will not be on the solidification microstructure impact. With prolonging of aging time, precipitates tend to be more evenly dispersed precipitation, aging time in 9h, the effect is best, and the hardness also reaches maximum. With the increase of material deformation, the tensile strength increase and elongation decrease.Experiments confirmed that in casting solidification process using vibration, stirring or rotation method, can effectively refine alloys. Magnetic field application in alloy preparation process has shown a unique role. In this experiment, different intensity of pulsed magnetic field are applied during solidification process, the results show that the external pulsed magnetic field can significantly refine the grain structure, and with the increase of magnetic field intensity and refinement effect is getting better and better, in the magnetic field strength is 300A, the effect is the best. While the magnetic field strength is 500A, the effect of grain refining slightly goes down.