Strengthening mechanism of 2219 Al-Cu alloy by room-temperature random vibration

Conventional thermal strengthening treatments face the challenges of high energy consumption, environmental pollution, and low coordination between strength and toughness. This study attempted to suppress these imperfections by proposing a novel approach that employed room-temperature random vibration (RRV). The microstructures were analyzed by scanning electron microscopy and transmission electron microscopy in detail. The 2219 Al-Cu alloy is in a tension–compression bidirectional stress state during random vibration, and its stress state changes with frequency, which induces dislocation movement and multiplication. The dislocation movement eventually develops into a dislocation network, resulting in the dislocation pinning effect. Notably, the dislocation migration promotes the diffusion of solute and forms solute clusters owing to tension–compression deformation. The content of the coarse second phase particles (CSPP) decreased greatly with a small narrow precipitate-free zone (PFZ) width after random vibration treatment. The tensile and yield strength were improved by 13.5% and 17.6%, respectively, after RRV treatment. The ductility increases simultaneously, differing from conventional heat treatment processes, which is attributed to the joint action effect of dislocations, second-phase particles, and solute clusters. The findings confirm a new route for Al-Cu alloys to obtain excellent mechanical properties and provide valuable insight into the strengthening mechanism of room-temperature random vibration.