Effects of Solute Atoms on 9R Phase Stabilization in High-Performance Al Alloys: A First-Principles Study

Recent experiments have proven that the 9R phase can dramatically improve the mechanical properties of Al alloys. This work aims to investigate the effects of solute atoms on 9R phase stabilization in Al alloys through first-principles calculations. Based on two distribution models of solute atoms, namely, the uniform distribution and the Fermi–Dirac distribution models, we discuss the influences of solute concentrations and finite temperatures on the increments of intrinsic stacking fault energy in the 9R phase structure. The results reveal that high-concentration solute atoms (Ga, Ge, Sc, Si, Sn, Sr, and Y) can promote 9R phase stabilization. Among them, the Sr atom shows the highest performance, but its stabilization can be disrupted by high temperature. These findings serve as a valuable guidance for designing and using high-performance Al alloys with the 9R phase structure.