Tensile fracture criterion of metallic glass

Abstract

The fracture criterion of metallic glass (MG) is still under debate so far. On the issue of describing the normal stress effect on the tensile fracture behaviors of MGs, there are two fracture criteria: the Mohr-Coulomb (M-C) criterion and the Ellipse criterion. In this study, the normal stress acting on the tensile fracture planes was controlled and varied in a wide range by introducing inclined notches with different inclination angles to a series of Zr-based MG specimens. Based on the experimental results, both the Ellipse criterion and the M-C criterion are compared and analyzed. The experimental results reveal that the Ellipse criterion gives a better prediction than the M-C criterion for the tensile fracture behavior of the investigated Zr-based MG in a wide normal stress range. Moreover, the pressure and normal stress effects were separately considered and some other criteria were further discussed. It is found that under tensile loading, the pressure effect is weak while the normal stress effect is strong. Combined with previously reported results for a variety of MGs, the Ellipse criterion is found to have the capability to describe all the different contributions of the normal stress effect and thus may be suitable as a unified tensile fracture criterion for all MGs with different fracture behaviors.