The newly developed metallic glasses (MGs) termed as nano-glasses (NGs) consist of glassy nanoparticles or nano-grains connected by glass-glass interfaces (GGIs) or boundaries. They are believed to be effective in enhancing the plasticity of MGs which might have a relatively low yield strength ADDIN NE.Ref.{D29D9BD3-E063-40AA-829E-8465DFCBF1E9}. The plastic deformation of NGs is attributed to the interaction between shear bands and the glass-glass interfaces or boundaries. The boundaries with high concentration of free volumes could act as nucleation sites for numerous shear transformation zones, giving rise to homogenous deformation in NGs. However, the intrinsic high concentration of free volumes in the glass-glass boundaries leads to the lack of a good combination of high mechanical strength and ductility of NGs. In this work, the influences of GGIs on mechanical properties of (Fe, Co)-based metallic nano-glasses as prepared by pulse electrodeposition are investigated. Computer simulation methods are developed to explore the improvement on mechanical strength and ductility of NGs through boundary engineering. The experimental and simulation results reveal that the mechanical properties of NGs could depend on the structural and composition inhomogeneities across GGIs. It is found that the issues of trade-off between mechanical strength and ductility in NGs could be resolved through boundary or GGI engineering. (* This work is supported by the Green Tech Funds # GTF202020103 from EPD of HKSAR, China)

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.