关键词: 镁锂锌合金, 室温力学性能, 加工软化, 显微组织, 脱锂, 原子扩散

Abstract: New-type sheets of Mg-6Li-3Zn and Mg-11Li-3Zn alloys were prepared by melting/casting, homogenization and hot/cold rolling. Their mechanical behavior at room temperature, microstructures after hot rolling and lithium loss phenomenon during hot rolling were all investigated. The tensile strength and true strain of fracture at room temperature of the two alloy sheets were measured as 208 MPa/0.13 and 170 MPa/0.375, respectively. The room-temperature relationship between true stress and true strain revealed that the work-hardening occurs in Mg-6Li-3Zn sheet while the work-softening occurs in Mg-11Li-3Zn sheet. The reasons why the work-softening occurs are that the β phase at room temperature is still in the range of recovery temperature, its stacking fault energy is low and the rapid diffusion of Li atoms in β phase reduces the generating rate of dislocation. The sheet microstructures after hot rolling consist of banded grains. It was found that the heavy lithium loss and lots of α phases appear during the hot rolling at 573?K of Mg-11Li-3Zn alloy sheet. The Li loss is caused by the extremely fast diffusion velocity of Li atoms and results in α phase increasing and β phase decreasing in volume fraction.