The rate sensitivity and plastic deformation of nanocrystalline tantalum films at nanoscale

Abstract

<p>Abstract</p> <p>Nanoindentation creep and loading rate change tests were employed to examine the rate sensitivity (<it>m</it>) and hardness of nanocrystalline tetragonal Ta films. Experimental results suggested that the <it>m </it>increased with the decrease of feature scale, such as grain size and indent depth. The magnitude of <it>m </it>is much less than the corresponding grain boundary (GB) sliding deformation with <it>m </it>of 0.5. Hardness softening behavior was observed for smaller grain size, which supports the GB sliding mechanism. The rate-controlling deformation was interpreted by the GB-mediated processes involving atomic diffusion and the generation of dislocation at GB.</p