Investigation on the dislocation evolution in nanoindentation with 2.5D discrete dislocation dynamics simulation and experiment

This study investigates the influence of materials' dislocation source density and initial dislocation density on dislocation evolution mechanism during nanoindentation process. On the basic of discrete dislocation dynamics (DDD) algorithm, a novel 2.5D nanoindentation numerical model was by proposed by coupling with finite element (FE) contact analysis. In particular, new reduced integration method and stress transmission mode were performed in this simulation scheme. Results showed that the dislocation multiplication and slip behavior were both significantly impacted by the initial dislocation source density. Meanwhile, the influence of initial dislocation density focused on the spatial arrangement of discrete dislocations. In addition, transmission electron microscope (TEM) analysis was used to reveal the dislocation configurations during nanoindentation process. Typical dislocation patterns including Shockley partial dislocation and Frank partial dislocation were found in extrusion region, which verifies the reasonable slipping conditions of DDD simulation. The results of this study can be useful in developing DDD model and predicting dislocation evolution rules in nanoindentation.