Brittle-ductile transition in notched nanoscale metallic glass specimens (INVITED)

Abstract eng:
Tension tests on nano-sized metallic glass (MG) specimens have reported large ductility including considerable homogeneous deformation followed by necking as opposed to failure by shear banding which is seen in bulk samples. The necking is triggered by shallow notches present on the specimen surface. In this work, finite element simulations of tensile loading of nano-sized notched MG specimens are performed using a non-local plasticity model to understand the deformation behavior from a mechanics perspective. It is found that plastic zone size in front of the notch attains a saturation level at the stage when a dominant shear band (SB) forms. This size scales with an intrinsic material length associated with the interaction stress between flow defects. Further, the ratio of the saturation plastic zone size to uncracked ligament length governs the brittle-to-ductile transition.

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