Stabilization of the plutonium delta phase in the plutonium-gallium-zirconium ternary phase equilibria system

The stabilization of the Pu delta phase in the Pu-Ga-Zr ternary phase equilibria system was determined. Twenty alloys were prepared. The alloys were homogenized at 4250C for 200 hours. The treatments used to promote the decomposition of the delta phase were: an anneal of 200 hours at 2250C and/or 400 hours at 2600C, 90% reduction by rolling at 2250C following by a 200 hour anneal at 2250C, isostatic compression to 1650C and 650 MPa for 30 minutes, isostatic compression followed by 200 hours at 2250C, and thermal cycling between +1000C and -850C. Decomposition of the delta phase was monitored by x-ray diffraction analysis and by density measurement. Samples representative of each alloy produced and of each identified phase were studied metallographically. The transformation characteristics were studied by dilatometry and differential thermal analysis