In-situ TEM study of crack propagation in crystal thinning area and crystal rotation at crack tip in Al

In-situ tension test in a transmission electron microscope (TEM) was used to study the fracture process of aluminium, as well as the real-time crack formation process and atomic-scale results of crack tip propagation were captured. The experimental results show that multiple Frank-Read dislocation sources are formed in the crystal thinning area at the front of the crack, and the nanocrack nucleates on the dislocation loops emitted by the dislocation source. The perfect dislocations that were continuously emitted from the crack tip slip and decompose in the crystal, resulting in the relative rotation of the crystal to form a twin boundary. After the perfect dislocation decomposition, a part of the residual dislocation formed a dislocation wall at the twin boundary to form a subgrain boundary, and the other part formed a stacking fault, and then the residual dislocation dragged the stacking fault to slip at the twin boundary.