Effect of the physical aging on the secondary β relaxation process in a La-based metallic glass

Dynamic mechanical relaxation processes, i.e., main (α) relaxation and secondary (β) relaxation, are important issues to understand mechanical deformation, atomic diffusion as well as glass transition phenomenon of metallic glasses. In current work, La68Ni15Al15Cu2 metallic glass was selected as a protocol glass system. Mechanical relaxation processes were probed by dynamic mechanical analysis. The effects of annealing at different temperatures were analyzed by Kohlrausch-Williams-Watts (KWW)-type equation. The Kohlrausch exponent βKWW reflects the deviation from a single Debye relaxation, indicating the fact that dynamics in metallic glass are actually heterogeneous originating from the structural heterogeneity. The effects of thermal treatments were also discussed, which provides a potential solution to tune the relaxation behaviors in metallic glasses.