Hydrogen behavior near surface regions in Mo and W studied by tritium tracer technique

Tritium tracer techniques are applied to observe behavior of hydrogen (tritium (T)) in near surface regions of Mo and W loaded by gaseous absorption (GAS) and a glow discharge (GDC). GDC produces blisters on both Mo and W surfaces and Tritium Auto-RadioGraph (TARG) showed the thickness of blister skins is larger than the escaping depth of T β-electrons, around 1 μm. For GAS specimens, T evolution is likely controlled by diffusion giving diffusion coefficients of, D Mo = 1.5 × 10 - 7 exp - 41 kJ / mol RT m 2 s - 1 D W = 4.3 × 10 - 9 exp - 38 kJ / mol RT m 2 s - 1 at 273–323 K. GDC specimens show much smaller diffusion coefficients with higher activation energies and T release continues very long, suggesting T release from blisters.