First-principles study of ternary fcc solution phases from special quasirandom structures

TL;DR

This study generates special quasirandom structures for fcc ternary solutions to accurately model their mixing behavior using first-principles calculations, providing a useful tool for understanding ternary alloy phases.

Contribution

The paper introduces new ternary fcc SQSs that closely mimic random solutions, enabling detailed first-principles analysis of their mixing properties.

Findings

Generated SQSs have correlation functions close to random fcc solutions.

First-principles calculations show minimal local relaxation in the SQSs.

SQSs effectively predict mixing enthalpy in the Ca-Sr-Yb system.

Abstract

In the present work, ternary Special Quasirandom Structures (SQSs) for a fcc solid solution phase are generated at different compositions, $x_A=x_B=x_C=\tfrac{1}{3}$ and $x_A=\tfrac{1}{2}$, $x_B=x_C=\tfrac{1}{4}$, whose correlation functions are satisfactorily close to those of a random fcc solution. The generated SQSs are used to calculate the mixing enthalpy of the fcc phase in the Ca-Sr-Yb system. It is observed that first-principles calculations of all the binary and ternary SQSs in the Ca-Sr-Yb system exhibit very small local relaxation. It is concluded that the fcc ternary SQSs can provide valuable information about the mixing behavior of the fcc ternary solid solution phase. The SQSs presented in this work can be widely used to study the behavior of ternary fcc solid solutions.