Microstructural investigation of uranium rich U–Zr–Nb ternary alloy system

Uranium rich U–Zr–Nb alloy system is a potential candidate among the family of alloys considered as metallic fuel for fast reactors application. As a part of the program U–7% Zr, U–5% Zr–2% Nb, U–3.5% Zr–3.5% Nb, U–2% Zr–5% Nb and U–7% Nb (composition in wt.%) alloys were prepared. The total amount of Nb and Zr was restricted, because higher addition of non-fissile alloying element not only reduces the fissile content it also decreases the breeding ratio due to parasitic absorption. The alloys were characterized by SEM micrograph. The phase analysis was performed with the help of XRD and the phase transformation temperatures were determined by DTA. The variation in crystal structure with subsequent replacement of Zr with Nb as an alloying element has been highlighted. The as quenched U–7% Nb alloy shows complete γ° phase at ambient temperature.