Reducing the sample size has become increasingly popular for quantifications of various mechanical size-effects, one of which is that virtually all stress-strain curves from metallic single crystals become intermittent, underlining that plastic flow is not a smooth process. Previous investigations on the intermittent stress-strain behavior of small-scale crystals have focused on the scale-freeness of displacement jump-size distributions, reporting pure or truncated power-law behavior that, via similar scaling exponents, suggest a universal aspect of plasticity, which is shared by vastly different microstructures and materials. However, investigating the time-resolved spatiotemporal avalanche dynamics of the same intermittent flow, revealed that there are indications for a materials-specific response, as expressed by different velocity relaxation behavior and average avalanche shape-functions in fcc and bcc crystals .
One fundamental aspect of our recent efforts in tracing nano-scale slip dynamics in single crystals is that there is a materials-dependent and test-system dependent range of finite slip velocities [2, 3]. Whilst the scatter of the recorded velocities is large and exhibits some agreement with recently predicted scaling laws, each so far investigated material has a recorded maximum slip velocity. The fact that finite values are seen, suggests that macroscopically smooth flow may be a manifestation of a time-scale mismatch between the internal processes, that is nano-scale slip (dislocation avalanches), and the applied rate. Here we investigate this proposition experimentally, by tracing the time-resolved nano-scale slip dynamics of Nb microcrystals across more than five orders of magnitude in displacement rate.
 G. Sparks, J. Sickle, K.A. Dahmen, R. Maass. Shapes and velocity relaxation of dislocation avalanches in fcc and bcc crystals, http://arxiv.org/abs/1705.06636 (2017).
 R. Maass, P.M. Derlet, J.R. Greer. Independence of Slip Velocities on Applied Stress in Small Crystals, Small 11 (2015) 341-351.
 G. Sparks, P.S. Phani, U. Hangen, R. Maass. Spatiotemporal slip dynamics during deformation of gold micro-crystals, Acta Materialia 122 (2017) 109-119.