Abstract
A method for preparing thin films of UC single crystals containing UC2 precipitates is described. The films have been examined by transmission electron microscopy and using selected area diffraction techniques the crystallographic relations between the UC2 and the UC matrix have been established. Twinning is observed in the UC2 precipitates and this is attributed to the interactions which occur when UC2 crystals of different orientation intersect. A mechanism is proposed for the formation of UC2 in slightly hyperstoichiometric UC.