Study of Mechanical Deformation in Bulk Metallic Glass through Instrumented Indentation

Instrumented sharp indentation experiments at the nanoand micro-length scales were carried out in an attempt to quantify the deformation characteristics of Vitreloy 1 bulk metallic glass. The experiments were accompanied by detailed three-dimensional finite element simulations of instrumented indentation to formulate an overall constitutive response. By matching the experimentally observed continuous indentation results with the finite element predictions, a general Mohr–Coulomb type constitutive description was extracted to capture the dependence of multiaxial deformation on both shear stresses and normal stresses. This constitutive response is able to provide accurate predictions of the evolution of shear bands seen in uniaxial compression tests. Constrained deformation of the material around the indenter results in incomplete circular patterns of shear bands whose location, shape and size are also captured well by the numerical simulations. The analysis is also able to predict the extent of material pile-up observed around the indenter. The surface deformation features are also consistent with mechanisms such as localized shear flow, serrated yielding and adiabatic heating, which are observed during macroscopic mechanical tests.  2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.