Microstructure characterization and mechanical properties of Mg-9Li-5Al-1Zn-0.6RE alloy

Mg-9Li-5Al-1Zn-0.6RE alloy was prepared by vacuum induction heating. The microstructure and phases composition of the alloy were analyzed with optical microscope, scanning electron microscope and X-ray diffractometer. Then the effect of homogenization temperature on microstructure and mechanical properties of the alloy was studied. The hardness of samples under different homogenization temperatures was measured. The results show that, the alloy is composed of a phase, β phase, Mg17Al12 and AlLi. RE added into the alloy is solved in a phase and β phase completely. After homogenization heat treatment, the needle-like a phase disappears. With the increase of homogenization temperature, the shape of a phase is spherical-like first, then vennicular-like, and large block-like finally. The variation of the shape of a phase causes the hardness of sample to change accordingly. The most favorable homogenization temperature for microstructure and mechanical properties is 150 ℃.