It was recalled that the mechanism of grain boundary migration remained unclear, largely because of a lack of dependable data on such migration. Another reason was that the activation enthalpy and pre-exponential factor were not independent of each other (due to the so-called compensation effect). A new activation parameter, the activation volume, could be used to understand the relationships between experimentally measured values.

L.S.Shvindlerman, U.Czubayko, G.Gottstein, D.A.Molodov: Materials Science Forum, 1996, 204-206, 45-54