Investigation into movable dislocation evolution feature and strengthening effect for metal twin Al from atomic perspective

It is an universal phenomenon that the dislocations are produced in metal plastic deformation, which will has a potential value in fundamental research field for metal strengthening and toughening if its evolution characteristics and laws are investigated. Therefore, this behavior of movable dislocation for metal Al is studied by atomic simulation, and the microscopic mechanism of metal strengthening and toughening are also revealed through studying the interaction between movable dislocation induced by nano-indentation and twin boundary. Furthermore, the movable dislocation features, and dislocation density, and hardness, and adhesive effect are analyzed, and the comparison between the single boundary height and the multilayer twin boundary height is conducted. It is found that the plastic deformation of aluminum mental can be dominant by coordinating the amorphous generation and hexagonal close-packed structure under high speed deformation. In the nano-indentation process, the twin boundary has two obvious effects on movable dislocation of moving changes: one is to hinder the dislocation from migrating, the other is to induce dislocation to produce a cell, which result in the dislocation entanglement and generation of cross slip, it is also the main reason why the metal has excellent mechanical properties of strengthening and toughening features. These results demonstrate that the local non-contact region on the surface of Al substrate can induce atomic mismatch spots to appear during loading, and when the distance between the twin boundary and the upper surface of the substrate decreases, the effects of dislocation winding and dislocation slip become more obvious, and the anti-adhesion effect also decreases. In addition, the twin boundary is treated as the propagation of plastic ring source in the dislocation emission process when substrate is continuously loaded. These results provide an important theoretical source for improving metal strengthening and toughening effect.