Heat treatment of dilute U-Fe alloys

Metallographic structure, precipitation hardening, and distribution of precipitates were studied on γ-quenched U-Fe alloys containing from 400 to 900 ppm of Fe. Neither β nor γ phases was retained in specimens water-quenched from 800° or 850℃, and only the α phase was observed. During the subsequent annealing, hardening was found to occur in one or two steps, caused by the precipitation of U₆Fe. This hardening appears to be similar in nature to that experienced with Al-Cu alloys. The size and number of precipitates in variously heat-treated specimens were measured by electron micrography. The results obtained are discussed, with particular reference to the effect of precipitates on swelling, and are compared with data from the Harwell group on the bubble density in α-U irradiated to 0.5 a/0 burnup. (author)