On the Physics of the Anomalous Characteristics of Fickian Diffusion of Fe and Other Transition-Element Impurities in Crystalline Al at Elevated Temperatures

As the critical constructive analysis, with using the thermodynamic and crystal-chemical approaches, of the related experimental data is shown, the anomalous (with respect to the Al selfdiffusion characteristics (DAl - the self-diffusion coefficient, D0Al - the entropy (frequency) factor of the self-diffusion coefficient, QAl – the self-diffusion activation energy (enthalpy)) quantities of D*, D0*, Q* of the transition impurity Fickian diffusion in Al in many cases can be of the apparent character (related to the known Oriani model), whereas the normal quantities of D, D0, Q (i.e., close to DAl, D0Al, QAl), and the anomalously low quantities of D⊥, Q⊥, D0⊥ can be as the true characteristics of the impurity Fickian diffusion in the normal Al lattice (bulk) and in the compound-like nanosegregation (CLNS) structures at dislocations, respectively.