The effect of Sc on plastic deformation of Mg-Sc binary alloys under tension

An investigation into the effect of scandium on the mechanical properties of dilute binary Mg-Sc alloys deformed under tension has been conducted at 298 K, 78 K and 4.2 K. The relatively small improvement in strength and ductility is discussed in terms of the effect of Sc on texture, deformation modes and solute strengthening. Constitutive modelling results predict an increased relative activity of prismatic 〈a〉 and 〈c+a〉 slip with Sc solute addition. A minor decrease in stacking fault energy (SFE) of Mg due to Sc addition and its small atomic size are considered as determining factors in overall mechanical properties of alloys. No significant effect of alloy composition on strain rate sensitivity (SRS) is observed. An activation distance, d≈0.2b, is measured at 298 K and 78 K and is interpreted as being determined by dislocation-dislocation interactions, which use sequential activation of component partial dislocations during dislocation cutting.