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 2wt% 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.