First-Principles Study on Preferential Energetics of Mg-based Ternary Alloys Revisited by Short-Range Order in Disordered Phases

TL;DR

This study uses first-principles calculations to explore how short-range order influences the formation of LPSO structures in Mg-based ternary alloys, revealing correlations between SRO tendencies and LPSO stability.

Contribution

It provides new insights into the relationship between short-range order preferences and LPSO formation in Mg-based alloys using first-principles methods.

Findings

RE-Zn and Gd-Al pair clusters' probabilities increase, indicating a tendency towards LPSO formation.

La-Zn pair clusters' probability does not increase, correlating with the absence of LPSO structures.

SRO preferences are strongly linked to the potential for L12-type ordering and LPSO stability.

Abstract

To investigate the formation of Mg-based long-period stacking ordered (LPSO) structure, we systematically study the preference of the short-range order (SRO) in metastable disordered phases of Mg-RE-Zn (RE = Y, La, Er, Ho, Dy, Tb) and Mg-Gd-Al ternary alloy systems through first-principles calculation. RE-Zn (RE = Y, Er, Ho, Dy, Tb) and Gd-Al pair clusters' probability showed the tendency of increasing. In contrast, La-Zn pair clusters' probability is not increasing, whose system dose not form LPSO structure. This preference of SRO in disordered phases of Mg-based ternary alloys certainly indicates that peculiar L12-type ordering in LPSO as well as possibility of LPSO formation should have strong correlation with SRO tendency of energetically competitive disordered phases.