Shear localization and damage in metallic glasses at high homologous temperatures

Abstract

Studies of shear localization and fracture behavior in bulk-metallic glasses (BMGs) have been primarily limited to temperature regimes well-below the glass transition temperature. In this work, we investigate the shear localization and damage behavior of BMGs at temperatures within the supercooled liquid region where manufacturing processes of components made out of BMGs typically take place.

To model the deformation behavior of BMGs, we use the constitutive model developed by Thamburaja and Ekambaram (2007) and augment it to include a damage/fracture criterion. The modified constitutive model is then implemented in the ABAQUS (2008) finite-element program by writing a user-material subroutine. The material parameters in the constitutive model is then fitted to stress-strain curves obtained from a set of simple compression experiments conducted by Lu

et al. (2003) under various strain-rates at an ambient test temperature within the supercooled liquid region. With the model calibrated, we study the shear localization and damage behavior of the aforementioned Zr-based BMG by performing FEM simulations at various temperatures within the supercooled liquid region. Our simulations show that the orientation of the shear bands with respect to the loading direction are strongly sensitive to the ambient test temperature and specimen geometry.

Finally, we show that with the aid of finite-element simulations, potential spots of damaged material can be determined from a simulated net-shape forming process of a metallic glass component.