Microstructures, mechanical properties and corrosion behaviors of Mg–Y–Zn–Zr alloys with specific Y/Zn mole ratios

• Three Mg–Y–Zn–Zr alloys with specific Y/Zn ratios were studied for high strength.
• A wide distribution of compact X-phase lamella play a key role to the properties.
• A high performance wrought Mg alloy was prepared by casting and extrusion.
• The extruded MgY3.8Zn3Zr0.18 owns both high strength and good corrosion resistance.

Three Mg–Y–Zn–Zr alloys have been designed with specific Y/Zn mole ratios around 1.32 for the purpose of high performance. Microstructures, mechanical properties and corrosion behaviors of the alloys have been studied. A wide distribution of compact and thick X-phase could promote the mechanical properties and corrosion resistance drastically. Moreover, a solidification behavior was proposed to understand the alternant distribution of X-phase (Mg12YZn) and W-phase (MgY2Zn3). After hot extrusion, the corrosion resistance and mechanical properties of the alloys are strongly improved, due to the grain refinement and dispersive distribution of X-phase. Among the designed alloys, a high performance MgY3.8Zn3Zr0.18 alloy was prepared by conventional casting and subsequent hot extrusion process. It owns an ultimate and yield strength of 420 MPa and 300 MPa, respectively, as well as the best corrosion resistance.