Abstract
Mg-Sn and Mg-Zn alloys exhibit a strong age-hardening effect and have become promising bases for high-strength and low-cost Mg alloys. However, the atomic structures and phase stabilities of various precipitates and intermetallic compounds during the heat treatment in these systems remain unclear. Here we use a combined approach of first-principles calculations and cluster expansion (CE) to investigate the atomic structures and thermodynamic stabilities of the experimentally reported precipitates as well as orderings on the FCC and HCP lattices in Mg-Sn and Mg-Zn alloys. From the low energy structures searched by CE, potential Guinier–Preston (GP) zones are identified from preferred HCP orderings. The slow convergence for CE of HCP Mg-Zn, compared with that of Mg-Sn system, is attributed to the long-ranged interactions resulting from the larger lattice mismatch. This study could help design better age-hardened Mg alloys.KeywordsMg-SnMg-ZnPrecipitationFirst-principlesCluster expansion
Published Version
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