Effect of Ca and Nd Alloying on the Microstructure of Mg-6Al-Ca-Nd Alloy

The Mg-6Al-xCa-xNd alloys, which were alloyed by Ca and Nd element on basis of Mg-6Al alloy, were fabricated by gravity permanent mould method. The microstructure and mechanical property were characterized by scanning electron microscope (SEM) and X-ray diffractometer (XRD). Experimental results show that the microstructure of as-cast Mg-6Al alloy is with typical dendritic morphology, which is consist of α-Mg matrix and divorced eutectic β-Mg17Al12 phase along the grain boundaries. With increasing of Ca and Nd elements content, the α-Mg grains of Mg-6Al-Ca-Nd alloy were refined obviously, and the dendritic structure disappeared and equiaxed grains appeared. Meanwhile, β-Mg17Al12 phase decreased until disappeared and intermetallic Al-Ca phases and Al-Nd phases increased.