Two types of diffusion couple (U-23mol%Zr with U-23Zr-1.3mol%Ce and U-95mol%Zr with U-23Zr-1.3mol%Ce) were annealed isothermally at 1123 and 1023K in order to provide basic data on Ce diffusion in U-Zr alloys. Because the Ce solubility in the U-23mol%Zr alloy was less than 1mol% within this temperature range, Ce-rich precipitates were formed and dispersed in the U-23Zr-1.3mol%Ce alloy. The concentration profiles of Ce in the U-23mol%Zr/U-23Zr-1.3mol%Ce couples were analyzed on the basis of theoretical solutions of the 1-dimensional diffusion equation for a semi-infinite diffusion couple; each side of which was supersaturated with the diffusing substance. From this analysis, the diffusion coefficients of Ce in the U-23mol%Zr solid solution (γ-U, β-Zr) were estimated to be 2 x 10-13m2/s at 1123K and 6 x 10-14m2/s at 1023K. These were between the values extrapolated from reported self-diffusion coefficients for γ-U and β-Zr. In U-95mol%Zr/U-23Zr-1.3mol%Ce couples annealed at 1123 and 1023K, the concentration profiles exhibited an up-hill diffusion of Ce. The interdiffusion coefficients in this quasi-binary Ce-containing U-Zr system were obtained from the U or Zr concentration profiles and were compared with reported interdiffusion coefficients for the binary U-Zr system without Ce. The result indicated that Ce did not have a significant effect upon interdiffusion in the U-Zr solid solutions.

T.Ogata, M.Akabori, A.Itoh: Materials Transactions, 2003, 44[1], 47-52

Table 307

Diffusivity of H in U