First principles high-throughput screening to enhance the ductility of lightweight magnesium alloys

Abstract

The low ductility of lightweight magnesium prevents it from wide engineering applications, making it essential to improve its ductility. To provide guidelines to accelerate this improvement, we propose and test a hierarchical high-throughput screening approach for alloy design that is based on the quantum-mechanics-derived full general stacking fault (GSF) energy surface (\ensuremath{\gamma} surface), but simplified to examine only the unstable stacking fault energy (${\ensuremath{\gamma}}_{\mathrm{us}}$). We apply this approach to determine the promising dopant elements in Mg-$X$ binary alloys which may activate the pyramidal dislocations by decreasing GSF energy and thus improve the ductility of Mg. Ten elements, including Hg, Tl, Sn, Sb, Bi, Te, As, Pb, In, and Ca, are sifted out as promising alloying elements. Particularly, the Mg-Te alloy has the lowest ${\ensuremath{\gamma}}_{\mathrm{us}}$ of $156\phantom{\rule{0.16em}{0ex}}\phantom{\rule{4pt}{0ex}}\mathrm{mJ}/{\mathrm{m}}^{2}$ among all binary alloys, which is 25% lower than that of Mg ($209\phantom{\rule{0.16em}{0ex}}\phantom{\rule{4pt}{0ex}}\mathrm{mJ}/{\mathrm{m}}^{2}$), suggesting that it is the most promising alloy to enhance the ductility of Mg.