Correlations between the ductility and medium-range order of bulk metallic glasses

Understanding ductility or brittleness of monolithic bulk metallic glasses requires detailed knowledge of the amorphous structure. The medium-range order (MRO) of ductile Pd 40Ni 40P 20 and brittle Zr 52.5Cu 17.9Ni 14.6Al 10Ti 5 (Vit105) was characterized prior to and after notched three-point bending tests using variable-resolution fluctuation electron microscopy. Here, we show the presence of a second larger MRO correlation length in the ductile material, which is not present in the brittle material. The second larger correlation length accounts for an increased heterogeneity, which seems to enable an easier shear band formation and thus explain the difference in deformability.