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 alpha-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 degrees 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 degrees C, the quasicrystal is almost completely dissolved into the matrix only with 1-5 mu m tiny quasicrystals remained. Refinement of quasicrystal can markedly reduce the wear resistance, but increase the corrosion resistance.