Visualization of Microscopic Hydrogen Diffusion in Polycrystalline Pure Ni Using an Ir Complex

Microscopic hydrogen visualization has long been required to clarify the hydrogen embrittlement mechanism of metallic materials. In this study, hydrogen diffusion depending on microstructure in polycrystalline pure nickel film was successfully visualized using an Ir complex, whose color changes with hydrogen. The hydrogen flux in nickel was found to be large at random grain boundaries and small inside grains and at coincidence site lattice grain boundaries.