Quasicrystal dissolution and performance of isothermally heat-treated Mg–Zn–Y alloy

Conventional casting method was employed to prepare Mg–Zn–Y alloy only with α-Mg+I-phase; however, the grain size of quasicrystal is quite large in the as-cast state. Therefore, isothermal treatment was applied to refine the quasicrystal phase. The result shows that after the Mg–Zn–Y alloy was isothermally treated at 500 °C for several hours, the coarse quasicrystal can be gradually dissolved and thus refined. Generally, the dissolving processes of quasicrystal are slow first and then accelerate; after isothermally treated with 8 h at 500 °C, the quasicrystal is almost completely dissolved into the matrix only with 1–5 μm tiny quasicrystals remained. Refinement of quasicrystal can markedly reduce the wear resistance, but increase the corrosion resistance.