Mechanistic understanding, gamma phase formation and morphological behaviour of the Reduction−Diffusion processed U-Mo alloy

Reduction−Diffusion (R-D) process has been attempted to synthesize U-Mo alloy powder for the first time, and the mechanism of alloy formation has been investigated. Calciothermic reduction of uranium dioxide in the presence of the alloying element Mo, followed by high temperature soaking; subsequent leaching to remove the calcia slag yields U-Mo alloy in powder form. Experiments were carried out to synthesize U-10 wt%Mo alloy powder. The alloy powder products were characterized by Scanning Electron Microscopy and X-ray Diffraction. Complete stabilization of the metastable isotropic gamma phase has been achieved in U-10 wt%Mo powder synthesized by R-D process, where the final soaking was carried out at 1300 °C and 4 h. Attempts were made to understand the mechanism of formation of U-Mo alloy by R-D process on two fronts, i.e. alloying within a single particle, and particle-to-particle homogenization. The intended application of the alloy powders is in high uranium density dispersion fuels for high flux nuclear research and test reactors. •Reduction−Diffusion Process adopted for the first time to prepare U-Mo alloy.•Stability of cubic isotropic gamma phase achieved in the alloy.•The alloying mechanism in U-Mo alloy prepared by R-D process has been derived.•Effect of CaO slag morphology on the alloying and homogenization analyzed.•Schematic diagrams presented to explain the mechanism of R-D process.