Effect of Si and Zr on the interdiffusion of U-Mo alloy and Al

We investigated the effect of Zr additions to U-Mo and Si additions to Al on interdiffusion between U-Mo and Al by employing diffusion couple tests. We examined the phase stability of the γ-heat-treated alloys by high-temperature annealing tests. Using X-ray diffraction, we observed that the γ-phase U-7Mo-Zr alloys with more than 2 wt% Zr decomposed faster than the U-7Mo alloys. The diffusion couples showed that a Zr addition to U-7Mo and the addition of Si in Al reduced the interaction layer growth rates. However, Zr additions to U-Mo are most effective in reducing the overall interdiffusion rates when combined with Si additions to Al. The decomposition of the metastable U-Mo γ-phase during the diffusion test appears to have a significant effect on the overall interdiffusion rates.