Effect of Cooling Rate on the Solidified Microstructure of Mg-Gd-Y-Zr Alloy

The cooling rate has significant effects on the microstructure of Mg-Gd-Y-Zr alloy. It is found that the increase of cooling rate can refine the solidified microstructure obviously. The grains are refined and the morphology of the primary phases is changed from the coarse to the thin. With the increase of cooling rate, the eutectic distributes more homogeneously and its volume fraction decreases. Higher cooling rate can increase the solid solubility, which contributes to the reduction of dendritic segregation of solutes of Gd and Y in Mg-Gd-Y-Zr alloy.