Evident glass relaxation at room temperature induced by size effect

Abstract

Probing the relaxation dynamics of glasses at temperatures far below the glass transition remains challenging owing to the extremely slow relaxation characteristic and the lack of appropriate experimental techniques. We utilized a sensitive laser reflection curvature method to probe the slow relaxation dynamics of metallic glassy (MG) films of different thicknesses at room temperature. It was found that the relaxation dynamics of MG films can be dramatically accelerated by the thickness reduction, similar to the role of temperature. We also compared the size-induced relaxation of MG films to the relaxation of MG ribbons at varying temperatures. Similar effects of size and temperature on the relaxation dynamics are revealed. We show that a MG film with a thickness of $\ensuremath{\sim}10$ nm at room temperature has a fast relaxation dynamics equivalent to that of a bulk MG near the glass transition temperature within an observation time scale of 1 s, indicating that the liquidlike behavior in glass can be induced by size reduction. Our observation for MGs, similar to that of polymer glasses reported previously, suggests that the size-induced enhanced relaxation dynamics and glass transition is universal in glassy materials.