Structure refinement of pure iron during low-temperature high-pressure deformation

The structural evolution of iron (99.97%) during high-pressure torsion at the liquid-nitrogen temperature is studied by transmission electron microscopy and durometry. Twinning and deformation microband formation become operative low-deformation mechanisms along with dislocation slip because of a low dislocation mobility; as a result, deformation is nonuniform and inhomogeneous. Low-angle misorientations are retained up to the limiting achieved strains; therefore, a homogeneous submicrocrystalline structure, which forms in iron deformed at room temperature, does not form in this case. The structure refinement in iron during low-temperature deformation reaches a steady state.