Reshaping precipitate structure and morphology in an Al-Zn-Mg-Cu alloy through dislocation-precipitate interactions

Mechanical properties of age-hardenable alloys are significantly influenced by the intricate interplay between precipitates and mobile dislocations. This study examined how dislocations interact with nanosized precipitates at the atomic scale in an under-aged Al-Zn-Mg-Cu alloy. Results revealed that precipitates hinder dislocation movement but are also sheared by them during deformation. Furthermore, the sheared precipitates experienced structural collapse and deviated from their usual evolutionary path, forming ordered but non-periodic topologically close-packed structures and altered morphologies. The discoveries provide insights into dislocation-precipitate interactions and strain-induced structural changes, which could inspire strategies to modulate precipitates with tailored microstructures and thereby improved alloy properties.