The distortion regions near grain boundaries in cr-Fe-C solid solution were
studied by use of internal friction method. It was found that the total th
ickness of these regions is quite large though the thickness of real grain
boundaries is usually very thin. It was also found that the smaller the gra
in size, the thicker the total distortion region. A model for the structure
of distortion regions near grain boundaries is proposed. Their effects on
nanocrystalline materials are discussed.