Atomic insight into the shearing behavior of precipitates in an Al-Cu-Mg-Ag alloy

The interaction mechanism between the precipitates and moving dislocations is one of the key factors that governs the mechanical properties of precipitation-hardened aluminum alloys. In this study, for the first time, via a combination of atomic-resolution scanning transmission electron microscopy, image simulation, and first-principles density functional theory calculations, we have revealed the slip system for Ω′ precipitates in the Al-Cu-Mg-Ag system. Additionally, we re-examined the case for the Ω precipitates and discovered a different slip system from those previously proposed. This study demonstrates the workflow of determining the slip system(s) for nano-sized precipitates and the current results can shed useful insights into understanding dislocation-precipitate interactions and predicting the strength of Al-Cu-Mg-Ag alloys.