Dislocation Evolution in Pure Aluminum Subjected to Ultrasonic Vibration-Assisted Uniaxial Compression

Abstract

Revealing the influence of ultrasonic vibration on the dislocation evolution is the key to understanding its role in plastic deformation. In this paper, based on experiments and molecular dynamics simulations, ultrasonic vibration was periodically superimposed during the uniaxial compression of pure aluminum. The changes in average grain size, texture, and dislocation density under different vibration amplitudes were analyzed, and the mechanism of ultrasonic vibration altering the dislocation evolution was discussed. The results showed that when the ultrasonic amplitude is small, dislocation multiplication plays the dominant role, while with larger amplitudes, dislocation annihilation prevails, and the dislocation density comes to its peak at an earlier strain stage. Superimposing ultrasonic vibration increases the atomic kinetic energy, promotes dislocation generation and movement, induces subgrain rotation, reduces texture intensity, weakens the preferred orientation of deformed grains, and refines the grains.

Keywords: Ultrasonic vibration, Uniaxial compression, Molecular dynamics simulation, Dislocation multiplication, grain refinement