Revelation of the effect of structural heterogeneity on microplasticity in bulk metallic-glasses

Abstract

In this article, the shear-banding behavior in bulk metallic-glasses (BMGs) is studied using a focused ion beam (FIB)-based nanoindentation method, which involves cylindrical nanoindentation of a FIB-milled BMG microlamella and is capable of revealing the subsurface shear-band patterns down to the submicron scale. The results of the current study on a Zr-based BMG clearly show that short shear bands, with the lengths of a few hundred nanometers, could be severely kinked before growing into a longer one, which implies that structural heterogeneity plays an important role in the microplasticity of BMGs. Furthermore, through the three-dimensional finite-element simulation combined with the theoretical calculation based on the Mohr–Coulomb law, it is found that the yield strengths exhibit a large scatter as a consequence of the structural heterogeneity when microplasticity occurs in the Zr-based BMG, which is consistent with our recent findings obtained from the microcompression experiments.