Formation of high strength Mg–Cu–Zn–Y alloys

Quaternary Mg90(Cu0.667Y0.333)10−xZnx (x = 1.5, 3, 6) alloys, have been prepared by copper mold casting. Among these alloys, Mg90(Cu0.667Y0.333)10−xZnx (x = 6) alloy exhibits high ultimate compressive strength, over 700 MPa, and pronounced compressive plasticity, as high as 11.7%. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM) analysis reveal that the improvement of mechanical properties in the Mg base alloy is attributed to the formation of fine α-Mg dendrite and ternary eutectic phase (α-Mg + Cu2Mg + CuMgZn). It is also found that Mg90(Cu0.667Y0.333)4Zn6 alloy has some toughness fracture characterization. This work is expected to provide some hints for the composition design and processing technology of high strength magnesium alloys.