Abstract
U-Mo alloys were prepared by splat cooling technique and characterized by X-ray diffraction. The alloys with 11-12 at.% Mo show a stable gamma degrees-phase, while those with 13-17 at.% Mo exhibit a pure gamma-phase at room temperature.
All the splats become superconducting with T-c in the range from 1.24 K (pure U splat) to 2.11 K (U-15 at.% Mo). The phase transformation and stabilization of gamma-uranium phase in U-Mo alloys upon aging, annealing at 500 degrees C and 800 degrees C for time varying between 1 h and 144 h are described.
Annealing at 500 degrees C leads to a decomposition of the gamma-phase, while annealing at 800 degrees C has stabilized the initial gamma-phase in U-Mo splat-cooled alloys. The gamma-phase U-15 at.% Mo alloy is stable to hydrogen exposure at atmospheric pressure (1 bar) and at room temperature; it does not absorb any detectable amount of hydrogen.
Exposed to high pressure (80 bar) of H-2 gas it becomes hydride-powder (UH3Mo0.18) consisted of elongated particles of 1-2 mm revealing amorphous state. The hydrogen can be desorbed by heating to 500 degrees C in vacuum.