Neutron irradiation induced changes in mechanical properties of metals and alloys

The effect of neutron fluency on material properties was investigated. The items studied covered a wide range of crystalline materials, ferrous and non-ferrous materials were studied. FCC, BCC and HCP structures were dealt with. Low, medium and high melting point alloys were used Cu, copper alloys, Al, some aluminium allays, stainless steels (304 & 316) and some nickel base alloys which have FCC structure were subjected to fast neutron exposures. Fe and some iron alloys belong to BCC structure, while Mg and Zr alloys studied belong to HCP structures Some of alloying elements involved in alloy constituents have substitutional atomic positions, while others have interstitial sites. History of the material was also taken into consideration. Thus the study covered cold worked recrystallised, fully annealed and aged materials Neutron irradiation was mostly associated with brittleness, Cu and copper alloys showed significant radiation hardening which varied according to solute atoms characteristics. This hardening fitted straight line relation between strength increase and square root of fluence. Al-showed less strengthening effect compared to Cu. Alloys showed lower radiation hardening compared to pure metals. Cold worked structures showed lower strengthening and in some cases softening was observed compared to annealed material. Ni base alloys and stainless steel showed comparable radiation strengthening. Some nimonics showed radiation softening depending upon type of solute elements and their concentration. In some cases radiation improved age hardening effect, whereas in some other cases ageing characteristics were not changed due to radiation exposures. Saturation tendency was mostly observed with higher fluence 10(19) nvt. The higher the prior strength, the lower the radiation strengthening. These results were correlated with atomic configuration and neutron interaction with lattice defects.