Dislocation-mediated brittle-ductile transition of diamond under high pressure

P Wang and DX Zhou and HR Zhao and YC Lin and AM Nie and HT Wang, DIAMOND AND RELATED MATERIALS, 138, 110198 (2023).

DOI: 10.1016/j.diamond.2023.110198

Recent confirmation of room temperature dislocation plasticity in single-crystal diamond and the activation of 001<110> slip system in experiments has opened up a new era to understand the deformation mechanism of brittle covalent crystals. However, few theoretical research and simulation has been conducted on the dislocation gliding in 001<110> slip system. In this work, a new potential function is derived from the original Tersoff potential to the Tersoff High Pressure potential with a novel bond order term with the nearest neighbors. This model has been validated with series of molecular dynamic simulations of both 001<110> and 111<110> dislocation slip systems in diamond, successfully describing the dislocation mediated brittle-ductile transition under high hydrostatic pressure. The gliding mechanism of dislocation on 001 plane presents a jumping character with a large burgers vector under high hydrostatic pressure. Whereas, the diamond exhibits a zipper like Griffith cleavage upon shearing under zero hydrostatic pressure. Similar deformation processes are also found in polycrystalline diamond. The current model is expected to prove useful in related simulations focusing on the strengthening mechanism in diamond and related research.

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