Effect of Solid Solution Treatment on Microstructure and Mechanical Properties of Mg97Y2Zn1 Alloy

The X-phase grew in the matrix on the basal plane (0001) when Mg97Y2Zn1 alloy was solution treated at 415 and 540 °C. However, increasing the treatment temperature up to 560 °C, some X-phases may be dissolved. It was further observed that the dynamic recrystallization (DRX) process was completed and abnormal grain growth in the extruded alloy that was solution treated at 415 °C. On the other hand, the incomplete DRX process in the alloy treated at 560 °C was restrained by high content of induced yttrium in matrix. The Mg97Y2Zn1 alloys treated in the range of 415-560 °C exhibit excellent mechanical properties, among which the highest strength was obtained in the one treated at 560 °C. The high strength is believed to be owing to the ultra-fine grain, high density of plane faults of the long-period stacking structures, strain strengthening, and solid solution strengthening.