The trapping and transport phenomena of hydrogen in nickel

Abstract

Hydrogen thermal analysis experiments have been employed to study the trapping and transport phenomena of hydrogen in nickel. Dislocations in nickel act as trapping sites of hydrogen, and the hydrogen trap activation energy at dislocations appears to be lower than the activation energy for the bulk diffusion of hydrogen. It is suggested that both hydrogen trapping at grain boundaries and short-circuit diffusion through grain boundaries in nickel are present. The trap binding energy at grain boundaries is estimated as 20.5 kJ ⋅ mol-1. Using the hydrogen thermal analysis experiments, the solubility and diffusivity of hydrogen in nickel have been measured. The temperature dependences of those are described by C (H atoms/Ni atom) = 1.57 × 10-3 exp(-11.76 kJ ⋅ mol-1/RT) and D (m2 s-1) = 7.5 × 10-7 exp(-39.1 kJ ⋅ mol-1/RT), respectively.