ATOMIC MECHANISMS OF <100> AND <111> TILT BOUNDARY MIGRATION ON THE EXAMPLE OF NICKEL

Abstract

Fundamental differences in the understanding of the mechanism and values of the energy of activation of migration form a request for new studies of this scientific problem through clearly certified grain boundaries. The molecular dynamics method was used to analyze the dynamics of the atomic mechanism of migration of small-angle boundaries <100> and <111>, which showed that paired grain-boundary dislocations split during the boundary movement with the change of partner dislocations. The migration of small-angle slope boundaries <100> is realized by splitting and changing partner dislocations, as a result of the operation of this mechanism of displacement of atoms, a grid with square cells is formed. In the case of border migration <111>, there is also a mechanism of joint sliding of paired grain-boundary dislocations. Paired dislocations of boundaries <111>, unlike grain-boundary dislocations of boundaries <100>, have common sliding planes along which they can slide with a relatively low activation energy. During the migration of borders <111>, the combined action of both mechanisms was recorded: the joint sliding of paired grain-boundary dislocations and their splitting with the change of partner dislocations. In the process of migration, symmetrical sections are formed in the grain where the border was moving, which, by turning, "adjust" to the structure of another grain. Therefore, when migrating boundaries <111>, the cells of the atomic displacement grid have a hexagonal shape.