Formation and Relative Stabilities of Core-Shelled L12-Phase Nano-structures in Dilute Al-Sc-Er Alloys

• 来源期刊: 金属学报（英文版）
• 年，卷（期）: 2020,（12）
• 页码范围: 1627-1634
• 页数: 8页
• 语种: 英文

摘要

First-principles thermodynamic calculations were carried out at the interface level for understanding the precipitation of coherent L12-phase nano-structures in dilute Al-Sc-Er alloys.All energetics,relevant to bulk substitution,interface forma-tion,interfacial coherent strain and segregation,were calculated and used to evaluate the nucleation and relative stabilities of various possible L12 nano-structures.Only matrix-dissolved solute Er(or Sc)can substitute Sc(or Er)in L12-Al3Sc(or Al3Er).The inter-substitution between L12-Al3Sc and Al3Er is not energy feasible.Ternary L12-Al3(ErxSc1-x)precipitates tend to form the Al3Er-core and Al3Sc-shell structure with a sharp core/shell interface.Three possible formation mechanisms were proposed and examined.The effects of Er/Sc ratio and aging temperature on the relative stabilities of L12-phase nano-structures in Al were also discussed.