Much evidence suggests that the unusual properties of ultrafine-grained (UFG) metallic materials are determined not only by the small grain size, but also by the high defective concentration in the grain boundaries. The grain-boundary defects in this case may be not only dislocations, but partial disclinations as well. Direct structural analysis has shown a high density of these defects in the grain boundaries of UFG nickel produced by equal-channel angular (ECA) pressing. In the grain bulk, high-energy structural states with high continuous misorientations (high curvature of the lattice) have been detected as well. This paper deals with revealing via comparative electron microscopy the above structural states in distinct UFG materials (copper, nickel, and the complexly doped intermetallic compound Ni-18at.percent Al-8at.percent Cr-1at.percent Zr-0.15at.percent B) produced by various methods of severe plastic deformation (SPD).
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