A new strain fracture criterion for bulk metallic glasses under complex compressive loading

The existing fracture criteria for bulk metallic glasses (BMGs) are described by the stress state on fracture plane. However, they are incapable to predict the fracture behavior of BMGs under compression loading because the nominal stress of most BMGs remains unchanged once materials yield. In this study, a new strain fracture criterion for bulk metallic glasses under complex compressive loading is proposed. The yield and plastic deformation before fracture under compression loading are described by the Drucker-Prager (D-P) criterion and plastic normality rule. Furthermore, due to the elastic perfect-plastic behavior of nominal stress for BMGs, we choose the nominal stress to describe the D-P yield criterion, which is well coincident with the experimental results. The two typical BMGs of Zr52.5Cu17.9Ni14.6Al10Ti5 (Vit105) and Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (Vit1) are used as examples to analyze the fracture behavior of BMGs under complex compressive loading. In this case, the plastic behavior of BMGs depends on the deformation modes, and the results can well describe the increasing tendency of plastic deformation to the higher pressure. (C) 2018 Elsevier Ltd. All rights reserved.