In order to get more information about the Zener relaxation than ever reported and, furthermore, to elucidate the interrelation between the relaxation effect and diffusion phenomena, the Zener peak which appears around 500°C has been investigated in the range of 11.1 to 30.0 at% Al by means of the internal friction technique. The activation energy, H, and the term D₀ of the diffusion coefficient deduced from the relaxation time are roughly given by
H=73.4−71.8c(kcal/mol),
and lnD₀=5.35×10⁻⁴H−27.8(cm²⁄sec)
where c is the atomic fraction of Al, respectively. Referring to the result of inter-diffusion, it has been argued that the diffusion of Al atom is possibly responsible for the relaxation effect in Fe–Al system. A definite correspondence has been found to exist between the changes of the half-width and of the relaxation strength of the Zener peak against Al concentration.