Molecular dynamics-based cohesive zone representation of microstructure and stress evolutions of nickel intergranular fracture process: Effects of temperature

The crack-tip atomic stress distributions and microstructure evolutions of the intergranular crack in bicrystalline nickel at different temperatures. [Display omitted] •Molecular dynamics-based cohesive zone model is used to study intergranular fracture.•The relationship between the stress field and microstructural evolution is analyzed.•Temperature dependence of mechanisms of intergranular fracture is revealed.•The stress and opening displacement relations are obtained at different temperatures. In this study, we find microstructure mechanisms and stress distributions around the crack-tip of an intergranular fracture process in bicrystal nickel are strongly dependent on temperature by using a molecular dynamics (MD)-based cohesive zone model (CZM). At a lower temperature, deformation twinning occurs in the two opposite directions along the grain boundary, and the crack propagation eventually forms an intergranular fracture. As the temperature increasing, deformation twinning is becoming increasingly hard to occur around the crack-tip along the grain boundary but more readily to generate the slip bands, and the crack propagation will not form intergranular fracture along the grain boundary. Moreover, based on the calculation of CZM, the slip bands are stronger to prevent intergranular crack growth than deformation twinning around the crack-tip, and a high stress is found in the region of microstructure evolution near the crack-tip. The present results may provide useful information for understanding intergranular fracture mechanisms and stress distributions at the atomic-scale.