Effects of semi-solid isothermal process parameters on microstructure of Mg-Gd alloy
来源期刊：中国有色金属学报(英文版)2010年增刊第2期
论文作者：苏桂花 曹占义 刘勇兵 王玉慧 张亮 程丽任
文章页码：402 - 406
Key words：magnesium alloy; Mg-Gd alloy; rare earth; strain-induced melt activation; semisolid; isothermal treatment
Abstract: The effects of semi-solid isothermal process parameters on the microstructure evolution of Mg-Gd rare earth alloy produced by strain-induced melt activation (SIMA) were investigated. The formation mechanism of the particles in the process of the isothermal treatment was also discussed. The results show that the microstructure of the as-cast alloy consists of α-Mg solid solution, Mg5RE and Mg24RE5 (Gd, Y, Nd) phase. After being extruded with an extrusion ratio of 14:1 at 380 °C, the microstructure of Mg-Gd alloy changes from developed dendrites to near-equiaxed grains. The liquid volume fraction of the semisolid slurry gradually increases with elevating isothermal temperature or prolonging isothermal time during the partial remelting. To obtain an ideal semisolid slurry, the optimal process parameters for the Mg-Gd alloy should be 630 ℃ for isothermal temperature and 30 min for the corresponding time, respectively, where the volume fraction of the liquid phase is 52%.
