Avalanches and rate effects in strain-controlled discrete dislocation plasticity of Al single crystals

Three-dimensional discrete dislocation dynamics simulations are used to study strain-controlled plastic deformation of face-centered cubic aluminium single crystals. After describing the rate and size dependence of the average stress-strain curves, we study the power-law distributed strain bursts and find a universal power-law exponent τ≈1.0 for all imposed strain rates. This is then followed by the characterization of the average avalanche shapes which reveals the two key physical regimes in dislocation plasticity dominant at small and large strain rates, respectively. We discuss the dependence on the loading rate and compare our observations with previous studies of strain-controlled two-dimensional systems of discrete dislocations as well as of quasistatic stress-controlled loading of aluminium single crystals.