J. Phys. Colloques
Volume 51, Numéro C1, Janvier 1990Proceeding of the International Congress
Intergranular and Interphase Boundaries in materials
|Page(s)||C1-239 - C1-244|
INTERPRETATION OF GRAIN BOUNDARY NONEQUILIBRIUM IN TERMS OF GEOMETRICALLY NECESSARY AND STATISTICALLY STORED DISLOCATIONSW. LOJKOWSKI1, J. WYRZYKOWSKI2 et J. KWIECISKI2
1 UNIPRESS, High Pressure Research Centre, Polish Academy of Sciences, Sokolowska 29, PL-01-142 Warsaw, Poland
2 Institute of Materials Science and Engineering, Warsaw University of Technology, Narbutta 85, Warsaw, Poland
It is proposed that the energy of grain boundaries in the state of non-equilibrium caused by trapped lattice dislocations (TLDs) can be calculated based on the theory of geometrically necessary dislocations of Ashby. For that purpose products of TLDs dissociation can be divided into two groups : statistically stored (SSGBDs) and geometrically necessary (GNGBDs) grain boundary dislocations. Recovery of SSGBDs leads to the relaxation of short range strain fields close to grain boundaries. The energy of SSGBDs is only a small fraction of the energy of non-equilibrium grain boundaries. Most of this energy is related to the long range strain fields of GNGBDs. Grain boundaries which absorbed high densities of TLDs and therefore having a large number of GNGBDs are under a high driving force for sliding and migration.