Homogeneous and heterogeneous dislocation nucleation in diamond

HZ Yang and JW Xiao and ZW Yao and XN Zhang and F Younus and R Melnik and B Wen, DIAMOND AND RELATED MATERIALS, 88, 110-117 (2018).

DOI: 10.1016/j.diamond.2018.07.005

Dislocation nucleation plays a key role in plastic deformation of diamond crystal. In this paper, homogeneous and heterogeneous nucleation nature for diamond 1/6 < 112 > glide set dislocation and 1/2 < 110 > shuffle set dislocation is studied by combining molecular dynamics method and continuum mechanics models. Our results show that although heterogeneous dislocation nucleation can decrease its activation energy, the activation energy at 0 GPa for diamond heterogeneous nucleation is still in the range of 100 eV. For 1/6 < 112 > glide set and 1/2 < 110 > shuffle set homogeneous nucleation, their critical nucleation shear stress approaches to diamonds ideal shear strength which implies that those dislocations do not nucleate before diamond structural instability only by a purely shearing manner. While for 1/6 < 112 > glide set and 1/2 < 110 > shuffle set heterogeneous nucleation, their critical nucleation shear stresses are 28.9 GPa and 48.2 GPa, these values are less than diamond's ideal shear strength which implies that these dislocations may be nucleated heterogeneously under certain shear stress condition. In addition, our results also indicate there exists a deformation mode transformation for diamond deformation behavior at strain rate of 10(-3)/s. Our results provide a new insight into diamond dislocation nucleation and deformation.

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