In situ study on the bending strain field of a Zr-based bulk metallic glass with notch

Full understanding of the ductility enhancement mechanism of bulk metallic glasses (BMGs) requires investigations of the strain field evolution under constrained load, which is still unclear in experiments to date. The present work in situ studied the strain field evolution of Zr_50.7Cu₂₈Ni₉Al_12.3 alloy with notch defects under three-point bending through the digital image correlation technique. It was revealed that the deformation was dominated by the normal strain along the specimen length direction and the shear strain which were highly localized into band-like pattern. The results experimentally prove the localized strain in shear bands. A linearly proportional relationship between the magnitude of strain maxima and notch diameter was unveiled as well, which gave rise to bending behaviors linearly dependent on notch size. Moreover, the strain evolution with testing time suggested that the deformation might be accomplished by a two-stage process which induced the multiple deformation regions on fracture surface. Our results provide experimental data and useful information about the bending deformation of BMGs, thus would shed more insights on developing theoretical model of BMGs mechanical behaviors.