Gibbs Energy of Formation of U2Mo and U2Ti Determined by EMF Measurements in LiCl-KCl-UCl3 Melt

Abstract

Gibbs energy of formation of U2Mo and U2Ti intermetallic phases in U-Mo and U-Ti binary systems, respectively was determined employing electromotive force measurements in LiCl-KCl-UCl3 melt. U-Mo and U-Ti alloys corresponding to two-phase field U2Mo+Mo and U2Ti+Ti were prepared by vacuum arc-melting and characterized by X-ray diffraction. Single phase U2Mo and U2Ti intermetallics were also prepared and characterized to support the indexing of Bragg peaks in two-phase alloys. Temperature dependence of ΔfGU2Mo∘ and ΔfGU2Ti∘ were, respectively expressed asΔfGU2Mo∘(kJ/mol-atom)=(−144.9±1.5)+(63±3)×10−3T(K)ΔfGU2Ti∘(kJ/mol-atom)=(−116.2±1.7)+(60±3)×10−3T(K)Since there were no other experimental data available that could be used to compare present correlations, results by DFT calculations from earlier works were compared and discussed. LiCl-KCl-UCl3 melt was analyzed after completion of electromotive force runs by cyclic voltammetry and no identifiable redox features due to Mo or Ti species in melt were observed. This suggested that both alloys remained stable in the melt even after 100 h duration of electromotive force runs and there was no chemical leaching of Mo or Ti from the alloy.