The self-diffusion of 63Ni in monocrystals of the ordered intermetallic compounds was investigated. It was found that the activation energies for

diffusion perpendicular to, and parallel to, the hexagonal c-axis were almost the same and lay between 2.14 and 2.34eV:

 c-axis:     D(cm2/s) = 0.61 exp[-2.16(eV)/kT]

|| c-axis:     D(cm2/s) = 0.70 exp[-2.21(eV)/kT]

The Do values were direction-dependent and ranged from 0.5 to 0.8cm2/s. The experimental values of the D/D ratio were between 1.13 and 1.68; depending upon temperature.

H.Schmidt, G.Frohberg, H.Wever: Acta Metallurgica et Materialia, 1992, 40[11], 3105-11