The self-diffusivities of Co60 and Ni63 in cobalt-nickel solid solutions exhibit a greater activation energy below the Curie temperature (Tc) than above. Values of ΔQ=Q (ferromagnetic) —Q (paramagnetic) are approximately equal to RTc. This is interpreted to indicate that the increment in activation energy arises from an increase in the formation energy of a vacancy in the ferromagnetic lattice, with the additional binding energy arising from the interaction of a spin with the Weiss field.

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Diffusion of copper in nickel and aluminum has been studied by the residual activity technique in the temperature ranges of 850° to 1050°C, and 350° to 630°C, respectively. Diffusivities (cm2/sec) are expressed as DCu/NiCu/Ni=0.724 exp[−(61 000/RT)]DCu/AlCu/Al=0.150 exp[−(30 200/RT)]. Results have been compared with those calculated from the theories of diffusion based on charge and size difference between the impurity and the solvent atoms.

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