Flow serration in a Zr-based bulk metallic glass in compression at low strain rates

It is demonstrated that at slow strain rates (∼10−4 s−1) in compression, the dominant room temperature macroscopic deformation mode in a ductile Zr-based bulk metallic glass is single shear along the principal shear plane. The stress–strain curve exhibited serrated flow in the plastic region. Scanning electron micrographs of the deformed samples revealed regularly spaced striations on the shear surface. A detailed analysis of the observed serrations disclosed that they were intimately related to the striations on the shear surface, suggesting that the serrations were mainly caused by intermittent sample sliding. Further investigations were conducted using in situ compression experiments; video images showed that there was indeed a one-to-one correspondence between the intermittent sliding and flow serration. The current study therefore suggests that flow serration is a result of intermittent sample sliding. This result also implies that the principal shear plane, once formed, is the preferential site for additional shear band formation.