THERMAL COMPATIBILITY STUDIES OF UNIRRADIATED U-MO ALLOYS DISPERSED IN ALUMINUM

The thermal compatibility of centrifugally atomized U-Mo alloys with a luminium has been studied. The results of the investigations show that the U-2 wt% Mo/aluminum dispersions increase in volume by 26% at 400 degrees C after 2000 h. This large volume change is mainly due to the formation of voids and cracks resulting from nearly complete interdiff usion of U-Mo and aluminum. No significant dimensional changes occur i n the U-10 wt% Mo/aluminum dispersions. Interdiffusion between U-10 wt % Mo and aluminum is found to be minimal. The different diffusion beha vior is primarily due to the fact that U-10 wt% Mo particles are much more supersaturated with substitutional molybdenum than U-2 wt% Mo par ticles. The aluminum diffuses into the U-2 wt% Mo particles relatively rapidly along grain boundary with nearly pure uranium, forming UAl3 a lmost fully throughout the 2000 h anneal, whereas the molybdenum super saturated in the U-10 wt% Mo particles inhibits the diffusion of alumi num atoms. U-10 wt% Mo displays superior thermal compatibility with al uminum compared to U-2 wt% Mo. (C) 1997 Elsevier Science B.V.