Shurinov R. Orientation changes and regularity of cracks occurrence and development in the plastic deformation process of two-dimensional polycrystals of aluminium at room temperature

Object of researches: two-dimensional polycrystals of aluminium. The purpose: Establishment of physical laws of orientational and structural changes, mechanisms of cracks occurrence and development in the plastic deformation process of polycrystalline samples. Methods: the original optical technique which allows defining orientational changes in the sample іn situ in the deformation process. X-ray, electron microscopy, metallographic methods, full certification of grain boundaries, method of hydrostatic weighing for the density of the samples calculation were used. Results: It is shown, that in the plastic deformation process of two-dimensional polycrystals of aluminium the different ways of the orientational changes, connected with the sliding development, formation of primary and secondary rotation are possible. It is established, that the grain boundary fracture at plastic deformation of two-dimensional polycrystals of aluminium occurs as a result of of the main cracks propagation in the pores whichare formed on the grain boundaries of the general type in the recrystallization annealing process or at the deformation of the samples. The laws of orientational and structural changes which preceded to the occurrence of transcrystalline cracks are established. It is shown, that difference between mechanical characteristics, and also character of destruction of two-dimensional polycrystals of aluminium with a strengthening titanium nitride coating and the similar characteristics for the samples without the coating is connected with change of the sequence of occurrence and relax processes development in the plastic deformation process. Field of application: Physics of strength and plasticity.