Evolution of Local Densities During Shear Banding in Zr-Based Metallic Glass Micropillars

Abstract

Shear bands (SBs) play an important role in plastic deformation of metallic glasses (MGs), but the evolving mechanism of SBs is still elusive. We study the structural formation and evolution of SBs inside MGs with synchrotron X-ray nano-computed tomography. It is found that discrete low-density regions are created in the elastic deformation regime, which form SBs of density fluctuations under large plastic deformation. With further increasing plastic strain, the thickness of SBs increases, and their local densities decrease. Before the formation of cracks, the low-density regions in SBs gradually evolve into nanovoids with the matrix around densified. The results are significant for understanding the plastic deformation mechanism of glassy materials.

Keywords: metallic glass, Shear band, structural heterogeneity, plastic deformation, synchrotron X-ray nano-computed tomography