Deformation behavior and microstructure evolution of Al-Zn-Mg-Cu alloy under low-frequency vibration-assisted compression: Considering the relative amplitude

Abstract

The effect of superimposed low-frequency vibration (LFV) during deformation is somewhat similar to that of ultrasonic-vibration, however its mechanism is still unclear. In order to clarify the mechanism of LFV, the LFV-assisted compression experiments of Al-Zn-Mg-Cu alloy with different amplitudes were conducted. The length of the elastic deformation zone (LE) of the material was considered when selecting the relative amplitude parameters. The macro-mechanical response, distribution of secondary phases, dislocation evolution and microhardness were determined. The results show that LFV with different amplitudes exerted different effects on the material. LFV at vibration amplitude <LE exerted a superimposed effect on the elastic stress. The proportion of micron-diameter secondary phases with an equivalent diameter < 3 μm increased by 16.67 % and dislocation proliferation was promoted. LFV at amplitude >LE exerted the coupling effects of elastic stress superposition and plastic vibration softening. The proportion of micron-diameter secondary phases with an equivalent diameter < 3 μm increased by 42.77 %, the proportion of nanoscale precipitates with an equivalent diameter < 2.5 nm decreased by 63.21 %, and dislocation annihilation was accelerated. This study reveals the amplitude correlation to LFV mechanism and provides a new idea for the application of vibration-assisted forming.