Microstructure and mechanical properties of new Mg-Zn-Y-Zr alloys with high castability and ignition resistance

Complex studies of new Mg-Zn-Y-Zr system alloys have been carried out. The content range for the formation of the two-phase structure MgSS (Mg solid solution) + LPSO (long-period stacking ordered) in alloys of the Mg-Zn-Y-Zr system was determined by thermodynamic calculations. The effect of heat treatment regimes on microstructure, mechanical, and corrosion properties was investigated. The fluidity, hot tearing tendency, and ignition temperature of the alloys were determined. The best combination of castability, mechanical, and corrosion properties was found for the Mg-2.4Zn-4Y-0.8Zr alloy. The alloys studied are superior to their industrial counterparts in terms of technological properties, while maintain high corrosion and mechanical properties. The increased level of properties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.