Effects of hydrogen and carbon on thermally activated deformation in nickel

Deformation experiments were performed to determine the effects of hydrogen and carbon on the activation parameters for dislocation slip in nickel. The techniques used were isothermal stress relaxation and differential temperature measurements. These methods allowed determination of the activation enthalpy and activation area for dislocation motion in nickel and the effects of hydrogen and carbon on these parameters. The results show that hydrogen increases the dislocation mobility in Ni and in NiC alloys by reducing the activation enthalpy for dislocation motion, while carbon reduces the dislocation mobility by increasing the activation enthalpy. Hydrogen solutes decrease the activation area for dislocation motion in both pure Ni and in NiC alloys.