Molecular dynamics simulation of crack propagation behaviors at the Ni/Ni3Al grain boundary

The primary purpose of this paper is to study intergranular and transgranular crack propagation behavior at the grain boundary (GB) of Ni/Ni3Al by Molecular Dynamics (MD) simulation. Cracks are loaded in tension mode I. The stress-strain curves, the changes of dislocation network, the crack propagation speeds and the changes of interfacial energy are compared with those of two models. The results show that the yield stress of the intergranular crack model is greater than that of the transgranular crack model. It is found that the intergranular crack propagation does not extend along the GB, but the crack extends into the gamma' phase. In addition, the transgranular crack extends at an angle of 45 degrees and the dislocation moves on the slip system {1 (1) over bar1} [(1) over bar 01]. The transgranular crack model breaks completely under a small strain. Moreover, the tranagranular crack propagation results from deformation damage of the model, and its propagation mechanism is shear rupture along the slip plane. The intergranular crack initiates propagation at the most dense position of the slip bands.