Indentation size effects on the creep behavior of nanocrystalline tetragonal Ta films

Nanoindentation creep tests were carried out at maximum indentation loads from 500 to 9000 μN to study the indentation size effects (ISEs) on the creep behavior of nanocrystalline tetragonal Ta films. The experimental results show that the hardness, creep strain rate and stress exponent are all indentation size-dependent. The ISE on the creep behavior is explained by grain boundary diffusion and sliding, and self-diffusion along the indenter/specimen interface and along the free surface of specimen.