Medium range order of bulk metallic glasses determined by variable resolution fluctuation electron microscopy

Variable resolution fluctuation electron microscopy (FEM) experiments are implemented with hollow-cone dark-field transmission electron microscopy. Medium range order lengths of zirconium and iron based bulk metallic glasses and amorphous silicon nitride are determined from the FEM results. It shows that maximum normalized intensity variances of FEM images occur when their nominal resolution approaches the correlation length Λ of the amorphous materials. Additionally, differences in the length and magnitude of medium range order are compared between metallic and covalent bond amorphous materials.

► Variable resolution fluctuation electron microscopy (FEM) was successfully conducted in the hollow-cone dark-field imaging mode.
► Medium range order lengths of Zr- and Fe-based bulk metallic glasses were obtained from FEM results.
► The maximum normalized variance of FEM image was found occurring when the experimental nominal resolution approaches the correlation length of amorphous materials.