The effect of porosity and void on creep behavior of ultra-fine grained nano crystalline nickel

Abstract Molecular dynamics (MD) study of nano crystalline (NC) Ni having grain size ~4 nm with and without presence of porosity (porosity ~1 at%) and void in center (diameter ~0.3 nm ) has been performed separately using embedded atom method (EAM) potential. All the simulated creep curves have extensive primary creep and tertiary creep regimes, and existence of steady state creep deformation is hardly evident. The MD study reveals that the grain boundary diffusion is the governing mechanism of creep deformation in ultra-fine grained (~ 4 nm) nano crystalline Ni and the presence of porosity even if 1 at%, deteriorates creep properties of NC Ni more significantly compared to the presence of single small void in the center of NC Ni.