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Calculation of the Activation Energy of Self-Diffusion in Aluminium from Impurity Diffusion Data

The only applicable radio-isotope of aluminium is Al26. However, due to the weak intensities and the possible tracer hold-up in the surface oxide layer1 the accuracy of the self-diffusion coefficient is small compared with that of the most other fee metals. On the other hand self-diffusion measurements using an NMR-technique have been performed in the temperature range below 500 °C. The activation energies found in this investigations are 28 to 32 kcal/mol (see e.g.2). Contrarily, the tracer measurements at temperatures up to the melting point yield 34 kcal/mole for the self-diffusion energy3-4. Seeger et al.2 interprete the increase of the diffusion coefficient with the