Experiments and Modeling of Three-Dimensional Dendritic Morphology of Magnesium Alloy

Abstract

Magnesium alloys are one of the lightest structural materials. The mechanical properties of magnesium alloys are often affected by the dendritic microstructures. With hexagonal close-packed structure, the preferred growth direction of α-Mg dendrite was believed to be $\left\langle {11\bar 20} \right\rangle$, and different 3-D growth models were proposed. However, these growth models for α-Mg dendrites were divergent and not yet generally accepted. Recently, Mg-20 wt.% Y alloy was studied by synchrotron X-ray tomography to establish the three-dimensional dendritic morphology of magnesium alloy. According to the reconstructed results, the α-Mg dendrites grew along eighteen branches with six branches along $\left\langle {11\bar 20} \right\rangle$ in the {0001} basal plane, and twelve along $\left\langle {11\bar 23} \right\rangle$ in the non-basal plane. Based on the three-dimensional morphology of α-Mg (Y) dendrite, a cellular automaton model was developed to simulate the dendritic growth of magnesium alloy. Both the experimental and simulation results offer a deep insight in understanding the dendritic growth evolution of magnesium alloys during solidification.