Effects of Nd on microstructure and mechanical properties of as-cast Mg-8Li-3Al alloy

Effects of Nd on microstructure and mechanical properties of as-cast Mg-8Li-3Al alloy were investigated by OM, X-ray diffraction (XRD), EPMA, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the dendrites sizes of α phase were decreased by the Nd addition. When the amount of addition Nd was 1.6 wt.%, the alloy with the smallest α phase was obtained. The refining mechanism mainly owed to the increasing constitutional supercooling at the solidification front. Furthermore, the compound Al2Nd generated by the reaction of Al and Nd, which distributed at the phase boundary and inside β phase, could also restrain the growth of α phase. Nd could improve the tensile strength and elongation of Mg-8Li-3Al alloy, however, excessive Al2Nd might also become crack source and decrease the elongation.