Minor Al addition tuning relationship of crystal-like structures and fast β’ relaxation in Cu-Zr metallic glasses

Glassy dynamics, a fundamentally important yet long-standing issue of glass physics, is however crucial in understanding the intrinsic properties of metallic glasses. By means of mechanical spectroscopy, high-resolution transmission electron microscopy and molecular dynamical simulation, here we report the evolution of fast process in addition to the slow β relaxation in the Cu-Zr based metallic glasses due to minor Al elemental addition. It is revealed that the icosahedral crystal structures formed as a result of element addition leads to remarkable opposite changes in the broadness and asymmetry of the fast secondary relaxation mode. Moreover, we found that the relaxation strength of fast process increases with the increasing number of these low-energy state ordered atomic structures whereas its relaxation kinetics becomes to be slowdown. The outreach of the present work provides us insight into the dynamic nature of metallic glasses and its variation with chemistry from the atomic-scale structural viewpoint.