Ductile-to-brittle fracture transition in polycrystalline nickel under tensile hydrostatic stress
Large-scale molecular dynamics (MD) simulation was used to study the tensile deformation and failure of defective polycrystalline Ni at various external tensile hydrostatic stresses. A ductile-to-brittle fracture transition occurred. This fracture transition was attributed to the active void and crack propagations, and the suppressed activities of grain boundary (GB) and dislocation from the extra tensile hydrostatic stress applied. Moreover, this interplay between dislocation and GB can occur as dislocation emissions, trapping, absorption, and reflection and transmission, but these forms depend mainly on the local stress states and local geometric structures.