Structural relaxations of grain boundary (GB) and glass-glass interfaces (GGIs) play an important role in the mechanical behaviors of polycrystalline metals and metallic nano-glasses (NGs), respectively. Although the former has been well investigated by anelastic or mechanical spectrum measurement, for example, with a characteristic internal friction peak (T.-S. Kê, Phys. Rev. 71, 533 (1947)), such meaningful technique has not been applied to characterize the structural relaxation of GGIs in NGs as far. In this work, the structural relaxations in multicomponent TM-P (TM: transition metals Co, Fe, Ni or Zn) NGs with various averaged sizes (Davg) of glassy grains are investigated by anelastic measurements, which have been synthesized by a pulse electrodeposition method. The results provide direct evidences that a new glass phase could be formed at GGIs in NGs, as characterized by an activation energy (~0.9 eV) for glass transition at GGIs much different with that (~2.0 eV) in the interiors of glassy grains. From the analyses on the dynamical scaling for mechanical losses (Q-1) in the glass and supercooled-liquid (SC-liquid) states, i.e., Q^(-1)∝(〖ω)〗^(-n)where ω is the angular frequency, it is suggested that the atomic structures at GGIs in NGs with Davg<150 nm could be dominated by solid-like atomic clusters, whereas those in NGs with Davg>250 nm might be liquid-like. The size effects on the glass forming ability of NGs are also quantitatively measured by exponents of the dynamical scaling in the SC-liquid state, suggesting that NGs with Davg<40 nm could be good glass formers. The atomic structures at GGIs revealed in this work could facilitate the development of NGs with desirable mechanical properties through GGI engineering. 

Dr. Guangping Zheng is currently an Associate Professor in Department of Mechanical Engineering at the Hong Kong Polytechnic University. His research areas are computational materials science, nanomechanics, mechanical properties and deformation mechanisms of bulk metallic glasses, metallic nano-glasses and high-entropy alloys. He has published more than 240 papers in refereed journals.