Investigation of the residual stress-dependent hardness of amorphous alloys

Inelastic behavior of the amorphous alloys (also called metallic glasses) is believed to be determined by the inhomogeneous deformation caused by the initiation, multiplication, and interaction of shear bands. Chen and Jiang have done extensive instrumented sharp indention experiments on this kind of materials and observed clearly residual stress-dependent hardness. Moreover, the density of shear bands formed during indentation depends on the stress type, compressive or tensile. A generalized constitutive relation of amorphous alloys based on free-volume model is developed in this paper, followed by detailed three-dimensional finite element simulations of instrumented sharp indentation. The simulation agrees with the experimental observations regarding to the residual stress-dependent hardness and the distribution of the shear band density. A more detailed analysis also address how the dependence of hardness on residual stress is determined by the material properties.