Engineering ultra-strong Mg-Li-Al-based light-weight alloys from first principles

Abstract

Light-weight alloys are essential pillars of transportation technologies. They also play a crucial role to achieve a more green and cost-effective aerospace technologies. Magnesium-lithium-aluminum (Mg-Li-Al) alloys are auspicious candidates due to their promising mechanical strengths at low densities. We herein present a systematic first-principles investigation of the Mg-Li-Al-based alloys to provide insights for designing ultra-strong light-weight alloys. Initial analysis indicates that the Mg-Li-Al mixtures are not thermally stabilized into random-solid solutions. Following this hint, the base-centered cubic (BCC)-based intermetallics of Mg, Li and Al are investigated for their thermal and elastic stabilities.Three simple figures of merits are used to further assess their mechanical strengths. The most-frequently observed intermetallics are used to predict the yield strength of the hetero-structures from the recent experimental works. The rule of mixing works reasonable well to predict the mechanical properties of complex structures starting from isolated intermetallics.