Isothermal diffusion couple experiments were performed at 1023K in order to investigate diffusion in body-centered cubic alloys of the system. The samples covered the U-rich corner of the ternary phase diagram, with Pu concentrations of up to 27at% and Zr concentrations of up to 20at%. Interdiffusion coefficients were calculated for the common composition between 2 couples with intersecting diffusion paths. The Zr cross-interdiffusion coefficient, DZrPuU, was negative and had a magnitude which was twice that of the main coefficient, DZrZrU. On the other hand, DPuZrU was negligible when compared with DPuPuU. The latter coefficient was an order of magnitude greater than DZrZrU. Average effective interdiffusion coefficients were determined for all of the components over concentration ranges on the 2 sides of the Matano plane, as well as for the entire diffusion zone of the couples. It was noted that these coefficients increased with increasing Pu concentration, and decreased with increasing Zr concentration.

M.C.Petri, M.A.Dayananda: Journal of Nuclear Materials, 1997, 240[2], 131-43