Source-controlled yield and hardening of Cu(1 0 0) studied by in situ transmission electron microscopy

In the present work we investigate the mechanical properties of multiple slip oriented single crystal Cu(1 0 0) compression samples to shed light on size-dependent yield and hardening behavior at small-scales. Samples with diameters ranging from 90 nm to 1700 nm were fabricated using focused ion beam milling and tested in situ in a transmission electron microscope. The results demonstrate a dislocation source-limited size-dependent yield strength, as evidenced by size-dependent changes in the deformation morphology. Moreover, we report size dependency and strain dependency in the hardening behavior at these dimensions, where higher hardening is observed for smaller samples and at lower strains. This is explained by the source-limited nature of plasticity in small dimensions, which we demonstrate affects not just yield but also the hardening behavior in the nanopillars.