The tritium thermal desorption analysis for iron was carried out in order to elucidate the trapping sites of hydrogen and to obtain the activation energy of tritium desorption from each trapping site in iron.
The results obtained in this study are as follows;
(1) Four desorption peaks of tritium with maxima at about 500, 620, 900 and 1100 K, which were designated as peaks 1, 2, 3 and 4, respectively, were detected in both cold-rolled and annealed irons in the thermal analyses. This result suggests that there are at least four kinds of tritium trapping site in iron.
(2) The intensity of peak 1 which appears remarkably in the cold-rolled iron decreases by annealing the specimen.
(3) The total amount of desorbed tritium, namely the total amount of absorbed tritium, in the cold-rolled iron is much larger than that in the annealed one.
(4) The activation energies for desorption of tritium from the trapping sites were estimated. Peaks 1, 2 and 3 in the cold-rolled iron, they were estimated to be 56.5, 75.3 and 17.6 kJ/mol, respectively. Peaks 2 and 3 in the annealed iron, they were estimated to be 31.0 and 14.2 kJ/mol, respectively. Peaks 1 and 2 can be assigned as tritium release from dislocation and/or vacancy and iron nitride precipitate, respectively.
