Diffusion of 59Fe in single-crystal α-Zr

Diffusion coefficients D of 59Fe have been measured in single crystal α-Zr in the range 765-1193 K (in directions both parallel (D parallel to) and perpendicular (D perpendicular) to the c axis) and in a polycrystalline Zr-0.28 at.% Fe alloy, in the range 733-1070 K. The single-crystal results show that D parallel to/D perpendicular has values between 2.2 and 5.9, for T < 1143 K, and about 1.22, for 1154-1193 K; the persistence of the anisotropy beyond the nominal α-phase range (T < 1136 K) is surprising. The α-phase D parallel results show a complex temperature dependence which appears to parallel, to a notable degree, that shown by recent measurements of α-Zr self-diffusion. The D values for the alloy are about ten times less than the corresponding (average) single-crystal results. (author)