Determination of α/β phase boundaries and mechanical characterization of Mg-Sc binary alloys

In this study, α(hcp)/β(bcc) phase boundaries of the Mg-Sc binary phase system were determined by Mg/Sc diffusion couple and conventional equilibrated alloy methods. It was confirmed that α/β phase boundaries exist in regions with a higher Mg content than those in reported diagram. The Mg-Sc alloy with a β single-phase showed tensile strength of 254 MPa and elongation of 25.4%. The tensile strength of the Mg-Sc alloy increased with increasing volume fraction of the α phase (fα) and the alloy with a fα of 34% showed high UTS of 310 MPa and elongation of 28.8%, properties which are better balanced than those of conventional Mg alloys. This improvement was suggested to be due to isotropic deformation of the β phase, small grain size and small c/a of the α phase.