Chemical affinity can govern notch-tip brittle-to-ductile transition in metallic glasses

Chemical short-range order (CSRO) has emerged as an important index of material properties for multicomponent metallic alloys and glasses, but its role in transition between brittle and ductile fracture mechanisms is not understood. Here, using molecular dynamics simulations of fracture in notched samples of a nominally brittle metallic glass Fe80P20, we show that the fracture mode can be altered from crack propagation to shear banding by tuning​ CSRO. The underlying mechanism is identified as the agglomeration of metalloid (P) atoms as heterogeneous brittle zones with the formation of CSRO, leading to brittle fracture. By reducing the extent of CSRO, shear banding at the notch tip becomes the dominant failure mechanism. [Display omitted]