ON THE RELATIONSHIP OF THE CONTRIBUTIONS OF DIFFERENT CHANNELS FOR THE DISLOCATIONS STORAGE RATE DURING THE EVOLUTION OF A DISLOCATION ENSEMBLE IN THE PROCESS OF DEFORMATION OF POLYCRYSTALLINE NICKEL

10.25712/ASTU.1811-1416.2022.02.011

Abstract

Some aspects of the description of the dislocation ensemble evolution in the framework of the Kocks-Mecking phenomenology for coarse-grained materials or Mecking-Estrin for ultrafine-grained materials are considered. The use of the combined Kocks-Mecking-Estrin phenomenology in a wide range of grain sizes is argued and, on its basis, an assessment of the contributions of various dislocation storage channels (grain body and grain boundary) is proposed using the example of experimental data on uniaxial deformation of polycrystalline nickel samples with a grain size ranging from 0.7 up to 100 microns. It is shown that, as the grain size increases, the contributions of various dislocation production channels (grain body and grain boundary) may not be monotonic functions, and significantly depend on the characteristics of sample preparation, which determines the initial hardness of the material in terms of the ratio of dislocation density in the grain body and on grain boundary.