The migration energies for jumps into nearest-neighbour vacancies in these intermetallic compounds were correlated with static lattice Green’s functions which could be calculated from measured phonon dispersions. The present approach was an extension of the similar Schober-Petry-Trampenau approach which had been used earlier for body-centered cubic and face-centered cubic pure metals. In A3B compounds with the L12 structure, 3 first-nearest neighbour jumps into vacancies had to be distinguished and, in some cases, there was a bias between the final and initial configurations. As for monatomic lattices, the migration energy was split into 2 terms; one of which depended only upon the structure, while the other was a material-dependent term which was given by the Green’s function elements. The difference in size of the A and B atoms had to be taken into account, and the compounds had to be separated into 2 groups; depending upon the size of the majority atoms relative to the minority ones. The formulae were checked by computer simulation. The migration and bias energies were calculated for L12 compounds whose phonon dispersions had been measured. In the case of Ni3Al, other theoretical and experimental determinations compared well with the present model. A comparison of these energies with the critical temperatures of stability of the L12 structure revealed a significant contribution of ordering energy to the migration energy, for all 3 jump-types.

Migration Energies in L12 Intermetallic Compounds. E.Kentzinger, H.R.Schober: Journal of Physics - Condensed Matter, 2000, 12[37], 8145-58