Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge.Structural models proposed for bulk metallic glasses are still controversial owing to experimen...Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge.Structural models proposed for bulk metallic glasses are still controversial owing to experimental difficulties in directly imaging the atom positions in three-dimensional structures.With the advanced atomic-resolution imaging,here we directly observed the atomic arrangements in atomically thin metallic glassy membranes obtained by vapor deposition.The atomic packing in the amorphous membrane is shown to have a fractal characteristic,with the fractal dimension depending on the atomic density.Locally,the atomic configuration for the metallic glass membrane is composed of many types of polygons with the bonding angles concentrated on 45°-55°.The fractal atomic structure is consistent with the analysis by the percolation theory,and may account for the enhanced relaxation dynamics and the easiness of glass transition as reported for the thin metallic glassy films or glassy surface.展开更多
基金This work was supported by the National Natural Science Foundation of China(51672307,51801230,51822107,and 51671121)the National Key Research and Development Program of China(2018YFA0703603)+2 种基金the National Natural Science Foundation of Guangdong Province(2019B030302010)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB30000000)Beijing Natural Science Foundation(Z190010).
文摘Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge.Structural models proposed for bulk metallic glasses are still controversial owing to experimental difficulties in directly imaging the atom positions in three-dimensional structures.With the advanced atomic-resolution imaging,here we directly observed the atomic arrangements in atomically thin metallic glassy membranes obtained by vapor deposition.The atomic packing in the amorphous membrane is shown to have a fractal characteristic,with the fractal dimension depending on the atomic density.Locally,the atomic configuration for the metallic glass membrane is composed of many types of polygons with the bonding angles concentrated on 45°-55°.The fractal atomic structure is consistent with the analysis by the percolation theory,and may account for the enhanced relaxation dynamics and the easiness of glass transition as reported for the thin metallic glassy films or glassy surface.
