Determination of parameters of free volume model for Zr-based BMG via nanoindentation

Abstract The mechanical behavior of Zr55Cu30Ag15 bulk metallic glass (BMG) was investigated via the free volume theory. Spherical and Berkovich nanoindentation tests were conducted, and corresponding finite element models were constructed by implementing a pressure-dependent free volume model based on user material subroutine (UMAT). By performing a sensitivity study, two model parameters were selected as decisive parameters. Unlike Drucker-Prager model, the implemented free volume model properly describes (i) load-depth response and (ii) sub-indenter shear band and softening behavior from both spherical and Berkovich nanoindentations.