Shear banding and fracture behaviors of a bulk metallic glass studied via in-situ bending experiments with notched and un-notched specimens

Abstract The shear banding and fracture behaviors of Ti32.8Zr30.2Ni5.3Cu9Be22.7 bulk metallic glass (BMG) were studied via in-situ three-point bending experiments using notched and un-notched specimens. A notch strengthening effect was found based on comparing the nominal flexural strength of the notched and un-notched specimens. From in-situ observations of the notched specimens, it was found that the first shear band initiated near the notch tip was followed by a spate of shear band initiations in a wider range of locations, leading to macroscopic yielding. The shear band zone continued to grow until the specimen fractured, with plastic strain being accommodated by repeated branching of shear bands and increase of shear offset in the earlier formed parts of shear bands. Significant differences in the 3-dimensional orientation and shear offset direction of shear bands were observed between the notched and un-notched specimens. These differences were analyzed by relating the elastic stress fields in the general direction of shear band growth, obtained by finite element modeling, to the ellipse criterion.