STRUCTURAL, SUBSTRUCTURAL, AND ORIENTATIONAL CHANGES IN VARIOUS GRAINS OF POLYCRYSTALLINE ALUMINIUM SAMPLES IN THE PROCESS OF PLASTIC DEFORMATION

Abstract

The results of determination of orientation changes occurring on the surface of large-crystalline Al (99.96%) samples in situ during their plastic deformation under conditions of active loading with constant strain rate έ = 5∙10-5s-1 are presented. The studies were performed using the technique of obtaining color orientation maps from the specimen surface and subsequent visualization of color shades indistinguishable on it. This allowed us to obtain a number of new results regarding the orientational changes of grains and subgrains and to determine the possible mechanisms of such changes. For the first time the impact of disappearance of grain boundaries was detected and the mechanisms of grain reversal as a whole were determined. For a number of grains, a relay change in the orientation of subgrains in the grain from one boundary to another along the direction of sample stretching was recorded. It is experimentally shown that in this mechanism of orientational changes the maximum relative grain deformation is achieved. In the second case, the orientation changes of the grain as a whole are provided by a layer containing subgrains of 1…5 m in size, the orientation of which changes continuously during the deformation.