A dislocation-based crystal plasticity model for single-crystal micropillars based on strain burst with stochastic characteristics

The recent uniaxial micron-compression experiments exhibit the size effect and stochastic phenomenon such as stair-like fluctuation of the strain for the plasticity deformation of the single-crystal micropillars. Nevertheless, the current crystal plasticity theories fail to predict and characterize these phenomena due to lack of consideration of the related physical mechanisms. To compensate for such deficiency, this paper mainly aims to establish a dislocation-based crystal plasticity model for the single-crystal micropillars in the micro-compression to characterize the jerky fluctuation features by considering variational and stochastic micro-boundary conditions, which are controlled the dislocation source length. The new model is applied to investigate the size effect and stair-like fluctuation of the strain for single-crystal Ni with size from 2 to 20 μm by the finite element analysis. The predicted intermittent flows match well with those by experimental observations during the plastic flow. The simulation results reveal that the stress and the amplitude of the strain burst show obvious size effect and stochastic behavior.