The effect of interstitial impurities on radiation hardening and embrittlement in iron

Abstract

Previous studies have shown that a transition to brittle behavior at low temperatures is produced in Ferrovac iron when tensile tested at low temperatures after a fast neutron exposure of 2 sx 10 18 nvt at approximately 340°K. This embrittlement phenomenon has not been observed after an identical exposure at 203°K. Irradiation at 523°K above an apparent threshold exposure of approximately 1–2 sx 10 18 nvt and post irradiation annealing at 523°K and above also prevent the occurrence of brittle behavior in iron. The 203°K and 523°K irradiation temperatures also reduced the amount of radiation hardening produced by this exposure level although iron irradiated at 340°K required post irradiation annealing temperatures of 573°–623°K to reduce this effect. These data indicate that point defects or simple combinations of them with carbon are responsible for the hardening effects in irradiated iron but that a complex carbon-vacancy defect produces embrittlement.