DIFFUSION OF SN-113 IN THE INTERMETALLIC B82 COMPOUNDS OF THE SYSTEM NI/SN

The direction dependence of the diffusion coefficient of Sn-113 has been measured in single crystals of Ni6Sn39 by the layer grinding technique. The activation energies for diffusion parallel and perpendicular to the hexagonal c-axis are 2.93 and 3.07 eV, respectively, the D0-values 4.6 and 9.9 cm2/s. The experimental values of PHI = D(perpendicular-to)/D(parallel-to) are between 0.56 and 0.75 depending on the temperature. The experimental values are compared with theoretical values calculated for the different possible diffusion mechanisms. The main mechanism should be a normal vacancy mechanism superimposed by minority mechanisms the increase of which with rising temperature explains the temperature dependence of PHI.