  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.
