Hydrogen effects on nanovoid nucleation at nickel grain boundaries

We performed molecular dynamics (MD) simulations to study hydrogen effects on nanovoid nucleation at nickel grain boundaries using an embedded atom method (EAM) potential. Monte Carlo (MC) simulations were performed to introduce hydrogen atoms in low-angle and high-angle symmetrical [0 0 1] tilt boundaries at 300 K for analysis of plasticity and nanovoid nucleation. The simulation results show that hydrogen atoms were trapped at the grain boundaries and reduced the critical stresses and strains for nanovoid nucleation. The MD results also show that the effects of hydrogen on nanovoid nucleation depended on the grain-boundary hydrogen concentration regardless of the grain-boundary misorientations. The MD results were then inserted into a new hydrogen associated void nucleation model that operates as an internal state variable in the context of continuum thermodynamic plasticity.