Effect of Ti and Zr Combined Modification on Microstructures and Mechanical Properties of Mg₉₅Y_2.5Zn_2.5 Alloy Containing LPSO and W Phases

In order to develop a high performance Mg–Y–Zn alloy containing LPSO phase in the condition of lower Y/Zn atomic ratio, the effect of Ti and Zr on microstructures and mechanical properties of Mg₉₅Y_2.5Zn_2.5 alloy was investigated. Although the α‐Mg grains can be refined by adding Ti and Zr separately, the best refinement effect can be obtained by the combined addition of them. More importantly, the formation of LPSO phase was promoted by adding them in as‐cast Mg₉₅Y_2.5Zn_2.5 alloy. Meanwhile, the growth model of W phase was transformed from divorced eutectic to cooperative eutectic. In this case, the LPSO/W interface became continuous, which degraded the mechanical properties of as‐cast alloys. After extrusion, the increased LPSO phase caused by adding Ti and Zr greatly improved the strength of as‐extruded alloy.