Atomic-scale characterization of V-shaped interface structure of η₁ precipitates in Al–Zn–Mg alloy

Al–Zn–Mg alloys have attracted significant interest in the automotive industry owing to their high strength and light weight. Precipitation hardening is the primary mechanism by which these alloys are strengthened, meaning the analysis of the shape, size, and fraction of the precipitates is crucial. In this study, the interfacial structure of precipitates, which influences the mechanical properties of alloys, was investigated. Aberration-corrected scanning transmission electron microscopy studies revealed the atomic structure of the unique V-shaped interface structure of the η₁ precipitates, which are the most prevalent among the η precipitates produced in this alloy. The structure was investigated from an energetic perspective using first-principles calculations, which revealed that the formation of the V-shaped interface structure increased the stability through strain relaxation in both the aluminum matrix and η₁. The results provide valuable insights into the formation and growth mechanisms of precipitates, paving the way for further advancements in this field.