Effects of twist twin boundary and stacking fault on crack propagation of nanocrystal Al

The effect of twin boundary (TB) and stacking fault (SF) with different twist angles subjected to tension loading on crack propagation of nanocrystal Al is investigated using molecular dynamics simulation. The study reveals that the twist angle of grain boundary (GB) may have particular effect on crack growth, and that the GB with an appropriate twist angle may hinder the propagation of crack effectively. The results also indicate that for the models with twist TBs, the TBs with negative twist angles are more effective on obstructing crack propagation. Meanwhile, we found that the SF with positive twist angles hinder crack propagation more effectively than that of negative twist angles. It also shows that the GB disappeared during the deformation of the samples with SF twisted at −25° and −35°. Moreover, it is investigated from the results that the crack propagation rate varies with different temperatures, while the deformation mechanism is nearly unchangeable with the influence of the temperature. The study also demonstrates that the crack growth is related to nucleation of dislocations and twinning, as well as the deformation of GB.