The microstructure and the spectrum of grain boundary misorientations were studied in Armco Fe, following high-pressure torsion deformation, by means of transmission electron microscopy and orientation imaging microscopy. It was found that high-pressure torsion deformation results in the formation of an equiaxed grain structure with a mean grain size of 270 and 130nm using a shear strain of γ = 210 and 420, respectively. The misorientation spectra in high-pressure torsion Fe have a bimodal character with maxima in low (at 1 to 2°) as well as in high misorientation angle ranges. A marked increase in the fraction of special boundaries (Σ3–Σ45) was revealed as a result of high-pressure torsion.

Grain Boundary Statistics in Nano-Structured Iron Produced by High Pressure Torsion. Y.Ivanisenko, R.Z.Valiev, H.J.Fecht: Materials Science and Engineering A, 2005, 390[1-2], 159-65