Electronic Origin of Phase Stability in Mg-Zn-Y Alloys with a Long-Period Stacking Order

TL;DR

This study uses first-principles calculations to explore the electronic factors behind the phase stability of Mg-Zn-Y alloys with long-period stacking order, revealing the key role of Zn p orbitals.

Contribution

It provides a detailed electronic structure analysis explaining the phase stability of Mg-Zn-Y LPSO alloys, highlighting the importance of Zn p orbitals.

Findings

Zn atoms are stable even at half the Y atom concentration.

Bonding involving Zn p orbitals contributes to structural stability.

Convex hull analysis confirms the stability of the alloy phases.

Abstract

The origin of the phase stability of 18$R$ Mg-Zn-Y alloys with a long-period stacking order (LPSO) is studied using first-principles calculations. We calculate the heat of formation as a function of the number of Zn vacancies to discuss the role of Zn atoms. The calculated convex hull indicates that the Zn atoms in the LPSO alloys are stable even if they number about half of the Y atoms. The bonding state with Zn $p$ orbitals leads to the stability of the LPSO structure because the partial density of states of Mg nearest to the solute cluster forms a valley structure.