Effects of Cooling Rate and Component on the Microstructure and Mechanical Properties of Mg–Zn–Y Alloys

The microstructure and mechanical properties of Mg–6Zn–1Y and Mg–6Zn–3Y (wt%) alloys under different cooling rates were investigated. The results show that the second dendrite arm spacing (SDAS) of Mg–6Zn–1Y and Mg–6Zn–3Y is reduced by 32 and 30% with increasing cooling rates (R c) from 10.2 to 23 K/s, which can be predicted using a empirical model of \( {\text{SDAS}} = 68R_{\text{c}}^{ - 0.45} \) and \( {\text{SDAS}} = 73R_{\text{c}}^{ - 0.45} \), respectively. The compressive strength of both alloys increases with increasing the cooling rate, which is attributed to the increase of volume fraction (V f) of secondary phases under high cooling rate. The interaction of the cooling rate and component with SDAS has been theoretically analyzed using interdependence theory.