Unraveling the connection of electronic and phononic structure with mechanical properties of commercial AZ80 alloy

Magnesium alloys, particularly in the aluminum-zinc (AZ) series, are widely recognized for their remarkable strength-to-weight ratio. We performed electronic structure, lattice dynamics, and mechanical properties of the AZ80 alloy using first-principles density-functional theory. The influence of dilute alloying by Al/Zn was observed in electronic-structure of AZ80 through hybridization of Mg-(s,p) with Al-p/Zn-d states. The Allen’s electronegativity difference between Mg and Al/Zn was found to induce charge transfer mechanism that provides solid-solution strengthening and ductility, in agreement with experiments. The electronic and phononic band-structure was unfolded onto the primitive unit cell of pure Mg to provide key information related to structural distortions and disorder effects. Finally, the dynamic and mechanical stability of AZ80 were confirmed by phonons and Born-Huang criteria, respectively. Collectively, this study provides valuable insights into the fundamental properties of lightweight commercial grade AZ80, essential for application-oriented design of Mg alloys.