Atomistic insight into impact of solute segregation on ?-Mg/FCC-Al2Ca interface stability

Solute segregation at phase boundary (PB) is critical for stabilizing nano-precipitates, which plays a decisive role in designing Mg alloys with high thermal stability. To clarify the fundamental factors that govern the PB stability, impacts of solute Ag, Sn, Bi, and In on interfacial properties of coherent alpha-Mg (0001)/Al2Ca (111) were systematically investigated via first-principles calculations. Solute segregation was proven to affect the PB stability by both chemical and mechanical contributions. Feasible alloying elements that could stabilize the nano-precipitates should form strong bonding and/or alleviate the distortion near PB by segregation, wherein the former plays a more dominant role. Accordingly, Ag segregation at PB was deemed to improve the thermal stability of the Al2Ca phase. Our work aims to provide a new perspective for the development of Mg alloys for potential high-temperature applications via tailoring interfacial properties.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Solute segregation at the phase boundary (PB) is critical for stabilizing nano-precipitates in Mg alloys. The impact of solute elements (Ag, Sn, Bi, and In) on interfacial properties of α-Mg/Al2Ca was investigated using first-principles calculations. Both chemical and mechanical contributions of solute segregation were found to affect PB stability, with the former playing a dominant role. Ag segregation was shown to improve the thermal stability of the Al2Ca phase. This work provides a new perspective for developing Mg alloys with tailored interfacial properties for high-temperature applications.