A nanoscale study of nucleation and propagation of Zener types cracks at dislocations: Phase field crystal model

摘要

In order to clarify the specific causes of Zener-type crack initiation in the material and the characteristics during the crack propagation, the Phase Field Crystal model (PFC) is used to study the mechanism in nucleation and propagation of the Zener-type crack in the sample under constant displacement loading. The nucleation of the Zener cracks at dislocations and the formation process of the disclinations are observed. The results show that the Zener crack is nucleated and initiated by applied external strain at the dislocations. As the Zener-type crack initiates, the disclinations occur. The tensile strain at the crack applied by negative disclination is favorable to Zener-type crack nucleation and propagation. The crystal columns passing through Zener-type crack is deflected at the surfaces of the crack under the action of strain, and the deflection angle in the middle of the crack is the largest. A new method for calculating the strain field of atomic lattice samples is proposed by combining the Peak-Pair algorithm (PPA) with the PFC. The nanoscopic mechanism of the nucleation, initiation and propagation of the Zener-type crack can well be revealed by this method.