It was recalled that the Lifshitz-Slyozov-Wagner mechanism for the coarsening of a binary alloy depended upon the diffusion of minority B-atoms, through an A-rich matrix, from one precipitate to another. An alternative mechanism was the coagulation of large precipitates. Computer simulations and theoretical estimates were described which showed that, if the relevant diffusion mechanism was the exchange of neighboring atoms (Kawasaki dynamics), the Lifshitz-Slyozov-Wagner process always predominated; thus yielding a t1/3 dependence for the mean precipitate radius. On the other hand, if the diffusion mechanism was the exchange of an atom with a vacancy, then coagulation (t1/5) could predominate at intermediate times if the temperature was sufficiently low.

P.Fratzl, O.Penrose: Physical Review B, 1997, 55[10], R6101-4