Solute effect on the 〈a+c〉〈a+c〉 dislocation nucleation mechanism in magnesium

The generalized stacking fault energy (GSFE) curve plays a major role in predicting the properties of materials. In the present paper we estimate this GSFE curve for pure Mg and Mg with several alloying/solute elements, focusing on the pyramidal slip system of Mg. First-principles density functional theory can be used to calculate the GSFE curves to link continuum-scale dislocation properties and stacking fault widths, on pyramidal slip systems. Within the pyramidal slip systems, we specifically have considered pyramidal type I {101¯1}〈1¯21¯0〉, with 〈a〉〈a〉, and {101¯1}〈1¯1¯23〉, with 〈a+c〉〈a+c〉 dislocation, and type II {112¯2}〈1¯1¯23〉, with 〈a+c〉〈a+c〉 dislocation. Solute effects on these slip systems’ GSFE curves have been calculated for nine alloying elements: Al, Ca, Li, Gd, Ce, Si, Sn, Zn and Zr. The strength and ductility of these novel alloys can be qualitatively estimated in the light of pyramidal slip systems. Finally an approximate method to increase formability has been introduced by adding these solutes.