Thermal compatibility of centrifugally atomized U-Mo powders with aluminium in a dispersion fuel

The thermal compatibility of centrifugally atomized U-Mo alloys withaluminum has been studied. Samples of extruded dispersions of 24 vol.% spherical U-2 wt.% Mo and U-10 wt.% Mo powders in an aluminum matrix were annealed for over 2000 h at 400 C. No significant dimensional changes occurred in the U-10 wt.% Mo/aluminum dispersions. The U-2 wt.% Mo/aluminum dispersion, however, increased in volume by 26% after 2000 h at 400 C. This large volume change is mainly due to the formation of voids and cracks resulting from nearly complete interdiffusion of U-Mo and aluminum. Interdiffusion between U-10 wt.% Mo and aluminum was found to be minimal. The different diffusion behavior is primarily due to the fact that U-2 wt.% Mo decomposes from an as-atomized metastable γ-phase (bcc) solid solution into the equilibrium α-U and U2Mo two-phase structure during the experiment, whereas U-10 wt.% Mo retains the metastable γ-phase structure throughout the 2000 h anneal and thereby displays superior thermal compatibility with aluminum compared to U-2 wt.% Mo. (orig.)