A fast dynamic mode in rare earth based glasses

Metallic glasses (MGs) usually exhibit only slow beta-relaxation peak, and the signature of the fast dynamic is challenging to be observed experimentally in MGs. We report a general and unusual fast dynamic mode in a series of rare earth based MGs manifested as a distinct fast beta'-relaxation peak in addition to slow beta-relaxation and a-relaxation peaks. We show that the activation energy of the fast beta'-relaxation is about 12RT(g) and is equivalent to the activation of localized flow event. The coupling of these dynamic processes as well as their relationship with glass transition and structural heterogeneity is discussed. Published by AIP Publishing.