Radiation effects in commercial A-5 aluminum

Samples of A-5 aluminum, one of the common construction materials in nuclear reactors, were exposed to a thermal neutron (E < 0.625 eV) fluence of 1.0 x 10 exp 22 n/cm exp 2 , and a fast neutron (E > 0.625 eV) fluence of 0.7 x 10 exp 22 n/cm exp 2 . The maximum irradiation temperature was about 80 deg C. The samples were then punched to produce tensile and bending test specimens, and thinned for electron microscopical examination. CTEM, STEM and SEM analysis techniques were employed. The major effect that has been observed is the formation of Si-rich precipitates in the aluminum matrix, silicon being a transmutation product of aluminum. The precipitates were evenly dispersed in the matrix. Their exact nature has not been unequivocally identified. The tensile and bending tests did not show a significant change in properties before and after irradiation. This indicates a possible recovery of defects during irradiation, in accordance with previous findings. The irradiated as well as unirradiated fracture surfaces showed transgranular tearing and dimples, typical of ductile fracture. Consequently, in the irradiation doses used, commercial A-5 aluminum showed no apparent deterioration of properties. 1 ref.--AA