The formation of a deformation relief of crystals is considered as a way of relaxation of an applied stress. The process of self-organization of slip bands into structural elements of the deformation relief of a qualitatively new level (packs of slip bands, meso-and macrobands) is directed to reduce local stresses in the zone of their formation as compared to those in the region occupied by slip bands. It is established that the formation of a quasiperiodic deformation relief occurs under the conditions of Azaro-Tiller-Greenfield instability and critical wavelengths of the surface perturbations are calculated. Each type of structural elements of the deformation relief causes a certain local curvature of the surface and increases the magnitude of the local stress in the region of its formation. On an example of nickel monocrystals it is revealed that the maximum stress concentration on the surface of 8.2 times is caused by packed slip bands, macrobands cause a 6.3 times increase of the local stress and the minimum concentration value of 3.3 is typical for mesobands. Curvature radii of the convex zones are the largest for macrobands (r = 0.40 ± 0.04 μm) that facilitates the stress relaxation, while for mesobands it is the smallest (r = 0.050 ± 0.003 μm). It is shown that the process of self-organization of the deformation relief increases the size of a region with compatible strains that results in a longer preservation of the crystal integrity during deformation. On examples of f.c.c. single crystals of nickel, aluminum, ordered and disordered Ni3Fe alloy it is shown that the self-organization of slip bands into packs reduces the local stress in the packs formation zone by 1.8 to 3.5 times in comparison with slip bands. The revealed regularities are characteristic for materials with different stacking fault energies, types of sliding dislocations, and crystallographic features.
ASJC Scopus subject areas
- Materials Science(all)