Continuum level simulation on the deformation behavior of nanocrystalline nickel

A phase mixture based finite-element model was developed to study the deformation behavior of nanocrystalline nickel. The material was envisaged as a composite with two phases: grain interior phase and grain boundary phase. First, a systematic method was established to construct the digital topological model for the numerical simulation on real microstructure, which followed the experimental observed log-normal distribution. Then, a rate-dependent amorphous constitutive model was proposed for describing the grain boundary sliding behavior and a crystal plasticity model was conceived to define the grain interior phases. The numerical results on the mechanical behavior of nanocrystalline nickel with 20 nm mean grain size were in good agreement with the experimental ones presented in literature. From the presented evolution results on von Mises stress and equivalent plastic strain, it can be found that much faster plastic deformation in grain boundary phase occurs. Meanwhile, shear localization phenomenon and stress concentration at triple junction regions are obvious at all three given strain rates. These leads to the relatively lower ductility of nanocrystalline nickel compared with that of coarse-grain counterparts.