Rejuvenation behavior of Cu-Zr-Al metallic glass under different thermal treatment: Experiments and simulation

Abstract

Recovery-annealing and deep-cryogenic-cycling treatments have been applied to rejuvenate a Cu-Zr-Al bulk metallic glass from its relaxed state and as-cast state, respectively. The thermal treated samples all maintain an amorphous structure and show rejuvenated behavior with improved relaxation enthalpy and plasticity. The experimental and simulation results have revealed that the maximum stress decreased with a larger plastic strain for the rejuvenated samples. The significant stress drop becomes smaller after rejuvenation, which indicates a low activation energy for the shear flow events to occur. The rejuvenated samples possess a more heterogeneous atomic structure, with a lower fraction of icos+deficos and a higher fraction of bcc and fcc + hcp types cluster. Consistent with the results of the H-A analysis, the fraction of atoms with high local fivefold symmetry, such as (<0, 1, 10, x > and<0, 0, 12, x > ) decreases. These results may give a comprehensive understanding on the link between rejuvenation behavior under different thermal treatment and atomic structural evolution.