Stochastic nature of plasticity of aluminum micro-pillars

Micron-sized aluminum pillars, fabricated by focused-ion beam milling, were subjected to compression in a nanoindenter using a flat-ended tip to examine their deformation behavior. The deformation was jerky and the statistical distributions of the sizes of the bursts, their occurrence frequency, as well as the stresses at which they occurred were analyzed. The burst size was found to increase with stress in an approximately exponential manner. Post-mortem transmission electron microscopy investigation of the dislocation structures revealed that the dislocation density of the micro-pillars did not grow significantly after severe deformation. Based on the experimental observations, a Monte Carlo model was developed to describe the stochastic nature of deformation of these micro-pillars.