Investigation of Microstructure and Mechanical Properties of Centrifugal Casting Mg-Zn-Y-Zr Alloy
Mg-6wt%Zn-1wt%Y-0.5wt%Zr(ZW61) alloy was prepared by centrifugal casting and metal mould casting respectively.The as-cast microstructure and mechanical properties of the alloys were compared.The results show that the microstructure of centrifugal casting magnesium alloy is significantly refined,and its mechanical properties are improved.The microstructure and phase composition of ZW61 alloy were investigated through SEM and XRD.It was found that the matrix phase of both the alloys is α-Mg phase,and the second phase of ZW61 alloy are composed of I-phase(Mg3Zn6Y) and W-phase(Mg3Zn3Y2).According to the ImageJ software analysis,the area fraction of the second phase in the centrifugal casting alloy is lower than that in the metal mould casting alloy.In centrifugal casting process,the eutectic t ransformation of L → α-Mg + W and eutectoid transformation of L+ W→ α-Mg + I were suppressed,leading to the reduced amount of I-phase and W-phase,and form a solidification microstructure with the saturated primary phase consisting mainly of α-Mg phase.The centrifugal casting alloy has more plastic features than the metal mould casting alloy.