MODELING OF RECRYSTALLIZATION IN MECHANICALLY ALLOYED MATERIALS

The exceptionally high recrystallisation temperatures of ultra-fine-gr ained mechanically alloyed metals cannot be adequately explained in te rms of gamma' dissolution, dispersoid coarsening, or ordinary grain gr owth theory. Such alloys have an unusually fine grain structure before recrystallisation, the grain size typically being a fraction of a mic rometre. It is demonstrated here that in these circumstances. the fine grains cannot be treated as being topologically independent, because the grain-boundary junctions behave like strong pinning points, preven ting the easy nucleation of recrystallisation. A model based on this i dea, to new and published experimental data, are found to explain all of the known features of recrystallisation in mechanically alloyed oxi de dispersion strengthened metals. (C) 1997 Elsevier Science S.A.