Is neutron radiation exposure always detrimental to metals (steels)?

Abstract

It is well established that irradiated metals and alloys exhibit increased mechanical strength accompanied by reduced ductility, commonly referred to as irradiation strengthening and embrittlement. We talk about radiation damage and environmental degradation of metals following radiation exposure. Indeed, there have been numerous conferences and symposia held and planned on this subject, which include research work and discussions with the central theme being the damage created in materials by neutron radiation exposure. Radiation embrittlement in metals is believed to be due mainly to (1) changes in flow properties because of the interaction of dislocations with irradiation-produced defects¹, and (2) precipitation of transmutation-produced gases and irradiation-induced segregation at grain boundaries which are potential fracture sites². Contrary to the previously observed radiation embrittlement in metals, I report here that neutron irradiation of mild steel improved both the mechanical strength and ductility at 373 K even at relatively high (∼10¹⁸ neutrons cm⁻²), fast (>1 MeV) neutron doses. To my knowledge, such improvement has never been observed before.