Effect of crystal orientation on initiation and propagation of crack: Phase field crystal model study

The crystal phase field (PFC) method is used to simulate the propagation of the nano-crack of samples with different crystal orientations under the strain of the uniaxial tensile. The results show that the different crystal orientations have a significant effect on the initiation and propagation of the cracks. For the samples with the orientation angles of 5 degrees and 20 degrees, the notch is directly cracked due to the strain concentration at the dislocation of the crack tip. The cracks mainly show a mode of the brittle expansion, and its edges show smooth planar features. For the samples with the orientation angles of 10 degrees and 15 degrees, the dislocation is firstly emitted at the notch to generate vacancies by dislocation slipping. The vacancies grow and connect to form cracks. This process of the crack propagation belongs to the mode of the ductile crack with the rough edges. The results are consistent with that of the molecular dynamic and experimental results.