Microstructures and Properties of Melt-Spun and As-Cast Mg-20Gd Binary Alloy

Mg-20Gd(%, mass fraction) samples were prepared using melt-spinning and copper mold casting techniques. Microstructures and properties of the Mg-20Gd were investigated. Results show that the melt-spun ribbon is mainly composed of supersaturated α-Mg solid solution phase and the as-cast ingot mainly contains α-Mg solid solution and Mg5Gd phase. The differential scanning calorimeter (DSC) curve of the ribbon exhibits a small exothermic peak in the temperature range from 630 to 680°K, which indicates that the ribbon contains a metastable phase (amorphous). Tensile strength at room temperature of the melt-spun ribbon and as-cast specimen are 308 and 254 MPa, respectively. The elongations of the two samples are less than 2%. The fracture surfaces demonstrate that the fracture mode of the as-cast Mg-20Gd is a typical cleavage fracture and that of the melt-spun sample is a combination of brittle fracture and ductile fracture.