Brittle versus ductile fracture behaviour in nanotwinned FCC crystals

Molecular dynamic simulation (MD) was used to study the brittle versus ductile fracture behaviour in nanotwinned Face Centred Cubic (FCC) crystals subjected to the uniaxial tensile deformation. A fundamental brittle versus ductile fracture is observed, which can be mainly understood in terms of the ratio of surface energy to unstable stacking fault energy or the ratio of ideal tensile strength to ideal shear strength in atomic model with a confined range of twinning spacing. Results show that the small ratio value is favourable for the brittle fracture, and vice versa, the big one supports the ductile fracture.