Comparison of In Situ Micromechanical Strain-Rate Sensitivity Measurement Techniques

Strain-rate sensitivity (SRS) measurements using transient small-scale techniques are becoming increasingly popular for investigating nanostructured films and microcomponents since they can provide fundamental insights into the plastic deformation mechanisms within small volumes of material. Previously, researchers have typically used either nanoindentation or microcompression strain-rate jump tests on a variety of nanostructured materials and compared the resultant values with bulk compression data as a reference. However, no systematic comparison of the different transient micromechanical techniques has been performed on the same material to establish their relative merits or the consistency of their results. In this study, the SRS of nanocrystalline nickel is investigated using three independent, in situ, transient experimental techniques: miniature tension, nanoindentation, and micropillar compression. The obtained SRS exponents m measured by all techniques were found to be in good agreement, and the resulting apparent activation volume V-app of approximately 10 b(3) is consistent with grain boundary diffusion processes and dislocation glide-based plasticity.