Size effects in indentation measurements of Zr-1Nb-0.05Cu alloy

Indentation size effects (ISEs) have been studied in both indentation hardness measurement and indentation creep process of Zr-1Nb-0.05Cu. The continuous stiffness measurement (CSM) technique was used to determine hardness up to 2000 nm. The indentation creep tests were performed at room temperature with nominal initial depth from 100 to 2000 nm. It is shown that the hardness, activation energy and activation volume are all dependent on the indenter displacement. The ISE of indentation hardness relates to the theory of strain gradient plasticity. The course of activation volume versus hardness reflects the mechanism transition of indentation creep. For small indents, the diffusion through dense dislocations dominates the creep behavior. When the indents get larger, the deformation is governed by dislocation glide.