The validity of the Darken-Manning relationship between the interdiffusion coefficient and the tracer diffusion coefficient in ordered A3B alloys of L12 type was considered. The analysis centered on the Manning expression for the vacancy wind factor. The model used 6 atom-vacancy exchange frequencies which included inter-sublattice (a ↔ ß) and intra-sublattice (a ↔ a) jumps for both atomic components. Computer simulation was used to calculate the vacancy wind factor. In general, it was found that the actual vacancy wind factor was usually slightly larger than that predicted by the Manning formalism but, overall, it was clear that the Manning expression for this factor was very successful. The use of the Manning expression for the vacancy wind factor underestimated the interdiffusion coefficient by about 30 to 40%, at worst.

Test of the Validity of the Darken-Manning Relation for Diffusion in Ordered Alloys having the L12 Structure. I.V.Belova, G.E.Murch: Philosophical Magazine A, 1998, 78[5], 1085-92