Structural, microstructural and thermal analysis of U−(6-x)Zr−xMo alloys (x = 0, 2, 4, 6)

Uranium rich U–Zr–Mo alloys are considered to be good alternative fuel for fast reactors due to their many favourable properties to achieve higher burnup. Studies related to structural and microstructural characterization, phase transformation, thermal expansion and microhardness were carried out on U–6Zr, U–4Zr–2Mo, U–2Zr–4Mo and U–6Mo alloys (composition in wt%) where the total amount of alloying elements was restricted to 6 wt%. U–6Zr alloy is considered here as the reference composition and the effect of Mo addition in the U–Zr alloy has been investigated. The phase stability of alloys after water quenching and furnace cooling from high temperature bcc γ-phase was studied. The alloys undergo various transformations from high temperature bcc γ-phase to a variety of equilibrium and intermediate phases depending upon alloy composition and cooling condition. A significant change in the crystal structure, microstructure, phase transformation, solidus temperature, thermal expansion and hardness data was observed when alloying element Zr is gradually replaced with Mo.