Kinetics of carbon precipitation in irradiated iron

Abstract

Iron containing approximately 0.01 wt.% carbon was irradiated in the BNL reactor at different times and temperatures, and the amount of carbon in solution was measured by torsion pendulum internal friction. Isothermal annealings after irradiation for 12 days at 200°K showed that the irradiation accelerated the disappearance of carbon from solution by about three orders of magnitude over the thermal rate. The extent of the accelerated decay is a function of irradiation time, and after 12 days irradiation the peak decayed to background level. The decay curves are all second order with an activation energy of the diffusion of carbon in iron. After a 4 hr irradiation at 57°C, however, the decay was accelerated by only about one order of magnitude and the decay rate is not affected by further irradiation.