ON THE HIERARCHY OF DISLOCATION DESCRIPTIONS OF GRAIN-BOUNDARY STRUCTURES

A new approach to the study of hierarchical grain boundary dislocation structures is proposed. It is shown that the class of primary grain boundary dislocations (GBDs) is wider than that of lattice dislocations and includes GBDs of all favoured boundaries of the same misorientation axis. A simple analysis of the asymptotics of stress fields created by primary dislocation networks obviously shows the nature of higher-level (virtual) dislocations and allows to calculate their Burgers vectors not knowing the geometry of reference structures responsible for each level. An algorithm is presented for constructing the GBD hierarchy and determining the number of its members for any boundary with a given misorientation angle.