Role of indenter geometry on the deformation behavior in a Pd-Si based metallic and nanoglass

Nanoindentation experiments are performed on a binary Pd-Si metallic glass (MG) and nanoglass (NG) using Berkovich and cube-corner indenters to investigate the effect of indenter geometry on the deformation behavior. A large number of pop-ins in the load vs. displacement curves and a higher pile-up of material around the indenter are observed for sharper cube-corner indenter compared to the Berkovich indenter. In case of both the indenters, NG displays lower hardness than the MG due to the presence of higher free volume and lack of any clusters in the glassy grains or interfaces. Further, the hardness is observed to decrease with indentation load signifying the indentation size effect (ISE) in hardness. The discrete plasticity ratio, Ψ defined as the ratio of pop-in displacement, ∆hdis to the total displacement, htot is used to estimate the influence of serrations on total plastic deformation and characterize the nature of the plastic flow. The Ψ indicates that the deformation mode is independent of indenter geometry for both the glasses.