Solubility and diffusivity of protium in internally nitrided iron alloys

Some Fe-Ti and Fe-V alloys were internally nitrided by a plasma-treatment and their solubilities and diffusivities of protium were measured by an electrochemical method, using a 6M KOH electrolyte, NiOOH/Ni(OH)(2) counter electrode and Hg/HgO reference electrode. The protium solubility in the alloys increased by internal nitriding. Diffusivities of protium, in the internally nitrided alloys at ambient temperatures were in the order of 10(-9) cm(2)/s, which was much smaller than those in pure iron. Its activation energy was 30-40 kJ/mol. These values suggest that protium, in the internally nitrided iron alloys was supposed to be trapped and stabilized at the sites around the nitride precipitates, which had lower site-energies than that in pure iron.