Free Volume Study of Severely Plastic Deformed Pure Fe

There is a growing interest for investigation of free-volume type defects in SPD-processed ultrafine-grained materials. In the present work, excess free volume in pure Fe prepared by shaped rolling is studied by high-resolution differential dilatometer as well as Archimedes method. The results show the formation of excess volume with increasing deformation strain. The volume fraction of free volume detected by dilatometer is below the evaluation of Archimedes method maybe because of the existence of void in the deformed metal. Microstructural study by field emission type scanning electron microscope confirms the presence of voids.