Dislocation contribution to modulus defect in nanocrystalline pure metals

The characteristic properties of dislocations in nanocrystalline pure metals are discussed in detail. It is considered that nanocrystalline metals prepared by inert gas condensation and compaction method or gas deposition method would contain dislocation densities equivalent to almost one dislocation in each grain, in general. Modulus defect expected from these dislocations is estimated to be roughly 1%. Further, a sensitivity of dislocation pinning effect to a number of point defects introduced in the specimen, is shown to be smaller by a factor of more than 10-6 in nanocrystalline metals, than in coarse-grained metals. These figures seem to be in reasonable agreement with recent results of low-temperature irradiation experiments.