The diffusion of Al and Zr was investigated in the β-Zr(Al) phase at 1203 to 1323K by using single-phase diffusion couples of pure Zr against Zr–2.8wt%Al. The interdiffusion coefficients exhibited a small increase with increasing Al concentration, and obeyed a quadratic compositional relationship. The temperature dependence of the interdiffusion coefficients at various compositions was established. The activation energy for interdiffusion decreased linearly with increasing Al concentration. The intrinsic diffusivity of Zr was higher than that of Al in this phase field. The impurity diffusion coefficient of Al in β-Zr was determined by extrapolating interdiffusion coefficients to limiting concentration of Al, and was found to exhibit a temperature dependence of the form:

D (m2/s) = 5.567 x 10-6exp[-220.08(kJ)/RT]

A correlation between the impurity diffusion coefficients of various impurities in β-Zr, and the atomic radii of the impurity atoms, was established and could be described by the relationship:

log[D (m2/s)] = -14.57 + exp[4.84 - 30.22r(nm)]

A.Laik, K.Bhanumurthy, G.B.Kale: Journal of Nuclear Materials, 2002, 305[2-3], 124-33