Densification contribution as a function of strain rate under indentation of terbium-doped aluminophosphate glass

In this work, the strain rate effect on the deformation processes under Berkovich indentation of Tb-doped aluminophosphate glass has been investigated. It is shown that both densification and shear flow, adopted as main mechanisms of plastic deformation for oxide glasses, are strain rate sensitive. Moreover, the shear flow is assumed to be responsible for the strain rate sensitivity of densification. The densification contribution to the total plastic deformation is found to be greater for lower strain rate, and the same tendency is observed for the plastic flow. This, in turn, leads to the influence of the strain rate on the hardness values, manifesting as a softening of the glassy matrix with the decrease of strain rate caused by more intensive development of the densification and shear flow. The decrease of hardness with load increase is attributed to the involving and increasing contribution of the shear flow and fracture to the total deformation process.