Structural ordering governs stiffness and ductile-to-brittle transition in Al–Li alloys

Abstract

The trade-off of stiffness and ductility of metals has long plagued materials scientists. To address this issue, atomic structure designs of short-range ordering (SRO) to sub-nanometer and nanometer scales have received much interest in tailoring the atomic environment and electronic interaction between solute and solvent atoms. Taking an example of Al–Li alloy with high specific stiffness and reverse correlation of Young’s modulus and melting point, in this work, we investigate the SRO-dependent stiffness and intrinsic ductile–brittle properties by performing a full-configuration strategy containing various structural ordering features. It suggests that the short-range ordered arrangement of Li atoms can effectively enhance the stiffness while keeping ductility, playing a hydrostatic pressure-like role. Our findings present fundamental knowledge to enable high stiffness and ductility for solvent phases with low modulus through designing local short-range ordered cluster structures.