Influence of dislocations, twins, and stacking faults on the fracture behavior of nanocrystalline Ni nanowire under constant bending load: a molecular dynamics study

In this paper, constant load bending tests were performed on a nanocrystalline Ni nanowire specimen at different deformation temperatures using molecular dynamics simulation to investigate deformation behavior and mechanisms responsible for fracture. The nature of the fracture occurred in this nanowire specimen is found to transit from brittle to ductile as the temperature rises from 500 to 800K. Also, with an increase in temperature, the fracture strain is increased indicating more plastic deformation prior to fracture. In the case of 500K and 600K deformation temperatures, fracture occurred along the shear band due to slip-twin interaction. On the other hand, at comparatively higher deformation temperatures, such as 700K and 800K, twinning and detwinning mechanisms are responsible for accommodating large plastic strain before fracture thus imparting plasticity in the specimen. It has also been found that formation and collapse of the stacking fault tetrahedron causes fracture of nanocrystalline Ni nanowire at 800K.