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Abstract: In this article, we discuss the recent use of the high-resolution dynamic atomic force microscopy (DAFM) in mapping the nano-scale dynamical structural heterogeneity in thin film metallic-glasses (TFMGs). Our focus is laid on the major factors which can influence the structural contrast in the DAFM images, such as tip radius, free-amplitude, set-point amplitude and surface roughness. Finally, through a comparative study of different TFMGs and single-crystal silicon, we demonstrate that the DAFM technique is effective in distinguishing different nanostructures through their energy dissipation spectra. [Copyright &y& Elsevier]

Abstract: Starting from the nanoscale structural heterogeneities intrinsic to metallic glasses (MGs), here we show that there are two concurrent contributions to their microscale quasi-static shear modulus GI : one (μ) is related to the atomic bonding strength of solid-like regions and the other (GII ) to the change in the possible configurations of liquid-like regions (dynamic relaxation). Through carefully designed high-rate nanoscale indentation tests, a simple constitutive relation (μ = GI + GII ) is experimentally verified. On a fundamental level, our current work provides a structure–property correlation that may be applicable to a wide range of glassy materials. [Copyright &y& Elsevier]

Abstract: Unlike crystalline metals, which have a well-understood periodical structure, the amorphous structure of metallic glasses (MGs) is still poorly understood, particularly when such a structure rearranges itself at the nanoscale under external agitations. In this article, we provide compelling evidence obtained from a recently developed high-resolution atomic force microscopy (HRAFM) technique that reveals the nanoscale structural heterogeneity after thermal annealing in a Zr–Ni metallic glass. Through the HRAFM technique, we are able to uncover the annealing-induced fractal growth of the dense-packing phases in the binary MG thin film, which exhibits a fractal dimension of ∼1.7, in line with a two-dimensional diffusion limited aggregation process. The current findings not only reveal the evolution process of atomic packing in the annealed MG thin film, but also shed light on the possible cooling rate effect on the atomic structure of MGs. [Copyright &y& Elsevier]