Microstructure and mechanical properties of Mg-6Zn-0.5Y magnesium alloy prepared with ultrasonic treatment

Ultrasonic effect on microstructure evolution and mechanical properties of Mg-6Zn-0.5Y magnesium alloy was investigated. The results show that ultrasonic treatment can significantly modify the as-cast microstructure of Mg-6Zn-0.5Y alloy. With the application of ultrasonic treatment, the primary alpha-Mg phase transforms from coarse dendrites to nearly fine equiaxed grains, and the continuous I-phase at alpha-Mg boundaries is modified into discontinuous one. Interestingly, the area fraction of I-phase decreases after ultrasonic treatment. Besides, the tensile properties of Mg-6Zn-0.5Y alloy are apparently improved after ultrasonic treatment. Compared to those of the untreated alloy, the ultimate tensile strength and elongation of Mg-6Zn-0.5Y alloy are improved by 67 % and 56 %, respectively.