Shekhovtsov O. Rotational effects at plastic deformation of two-dimensional polycrystals with fcc-lattice

The object is two-dimensional polycrystals with fcc-lattice; the aim to establish the regularities of plastic deformation rotational mode arise and development at two-dimensional polycrystals with fcc-lattice straining under active tension conditions; the methods are X-ray analysis, optical microscopy, computer method of metallographic effort, in situ investigation of plastic deformation using a digital video camera, computer method of modeling of grain boundaries structure and determination grain boundary effective energy; the results of research about regularities of plastic deformation rotational mode arise and development at two-dimensional copper and aluminium polycrystals straining are presented. In experiments, various types of rotational effects – grain boundary rotation, grain rotation, broken, through, collective and secondary reorientation bands have been observed. A particular part played by special and close to special grain boundaries in grain boundary rotation and reorientation bands formation has been established. It is shown; that the rotational effects originate in grains which orientation does not allow to implement three slip systems necessary for the coordination of a grain deformation in two-dimensional polycrystals. The crystal-geometric model of rigid atomic structure of grain boundaries is considered, which takes into account not only complete but also partial atomic coincidences. The concepts developed allow to determine grain boundary effective energy depending on misorientation angle, to reveal primitive cell (containing only one coincidence site) in structure of special boundaries. The results of special boundary modeling show that the low energy of the latter is not determinate unequivocally by the density of coincidence sites but, to a greater extent, depends on density of the short period pattern of partial atoms coincidences within the primitive cell; the field is solid sate physics.