A study was made of 59Fe tracer diffusion in sub-microcrystalline material which had been prepared by means of severe plastic deformation. It was found that interface diffusion occurred at relatively low temperatures, and was accompanied by appreciable recovery and grain growth; as reflected by positron lifetime, transmission electron microscopic, optical microscopic, Vickers hardness and calorimetric data. Lower limits on tracer diffusivities in the interfaces were derived. These values were similar to, or slightly higher than, the extrapolated diffusivities of conventional grain boundaries. The tracer diffusion measurements for heavily plastically deformed samples, or after conventional plastic deformation, showed that recovery processes and crystal growth which occurred in a principal recovery stage at 500K were triggered by atomic defects which became mobile in this temperature regime and by the onset of diffusion in the interfaces.

R.Wurschum, A.Kubler, S.Gruss, P.Acharwächter, W.Frank, R.Z.Valiev, R.R.Mulyukov, H.E.Schaeffer: Annales de Chimie, 1996, 21[6-7], 471-82