Grain refinement of Mg-10Gd alloy by Al additions

摘要

The addition of Al to a Mg-lOGd alloy was found to lead to substantial grain size reduction during casting at concentrations between 0.8% and 1.3%. At these concentrations, Al_2Gd particles were found at the center of grains, and the orientation relationship [112]_(Al_2Gd) ‖ [2110]_(α-Mg), (110)_(Al_2Gd)‖ (0110)_(α-Mg) was found reproducibly between Al_2Gd and α-Mg, indicating that these are the heterogeneous nucleant particles that form in situ at these Al contents. Most of these nuclei were between 2 and 7 μm in size. Furthermore, little grain coarsening was observed during solution treatment, particularly compared with an alloy grain refined by Zr particles where substantial coarsening occurred. This appears to be because Al_2Gd particles restrict grain boundary motion during solution treatment.