doi:10.1016/j.physme.2009.03.011 Formation of self-similar structures on 001 {100} aluminum single-crystal foils under cyclic tension P.V. Kuznetsov, I.V. Petrakova, Yu.G. Gordienko 1 , E.E. Zasimchuk 1 and V.L. Karbovskii 1 Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634021, Russia 1 Kurdyumov Institute of Metal Physics NASU, Kiev-142, 03680, Ukraine We study the relief formed on 001 } 100 { aluminum single-crystal foils attached to thick aluminum alloy specimens under low-cycle fatigue deformation. The formation of specific surface structures on the aluminum foils is shown to relate to the foil  specimen and aluminum foil  its surface layer interfaces. Particularly, the formation of longitudinal macroscopic bands on the aluminum foil is explained by periodic distribution of compressive stresses arising at the foil  specimen interface. At the interface between the macroscopic bands and tweed structure with spacing ~ 2.8 Pm a fine tweed substructure of the submicron range is found. The periodic 2D lattices of various scale formed on the foils are self-similar in the linear size range from fractions to hundreds of microns. Copyright © 2009 ISPMS, Siberian Branch of the RAS. Published by Elsevier BV. All rights reserved. * Corresponding author Dr. Pavel V. Kuznetsov, e-mail: kpv@ispms.tsc.ru 1. Introduction Papers [13] investigate the formation of the macrosco- pic relief on differently oriented aluminum single-crystal foils that are rigidly attached to thick metal specimens un- der cyclic tension in the elastic deformation range. From the very beginning of loading the aluminum single-crystal foil is plastically deformed due to low critical shear stresses. The pattern of deformation structures formed on the foil surface is found to depend on the orientation of single-crys- tal foils and number of loading cycles. Most interesting results are obtained for single-crystal foils of cubic orientation. A specific relief is observed to form on the foil surface, which initially presents a set of macroscopic bands directed along the loading axis. Authors of [3] suggest that bands appear due to the hydrodynamic flow of the material along channels with a liquid-like (non- crystalline) structure, which are formed owing to self-orga- nization of vacancy defects in the mechanical field. The study of the relief microstructure of aluminum sin- gle-crystal foils shows [4, 5] that bands have no signs of plastic deformation while their adjacent regions are struc- tured into a regular square lattice with microscopic ext- rusions. This structure referred to as the tweed one [6] was earlier observed in [6, 7] in some surface regions of a thick aluminum single-crystal specimen under cyclic deforma- tion at room temperature as well as on the aluminum po- lycrystal foil surface glued to a thick aluminum specimen after cyclic loading at temperature 77 K [8]. In paper [9] the tweed structure is found on the surface of highly pure aluminum polycrystal foils under cyclic tension at room temperature. The height of spherical protrusions measured by the atomic force microscope in [4, 5] is ~ 0.6 Pm. Paper [4] shows that at constant strain amplitude and frequency further cyclic loading of specimens leads to the formation of a 3D rhombic lattice of macroscopic extru- sions and intrusions with typical spacing 10 200 Pm, height 10 100 Pm and pores 1100 Pm in size. The analysis of our own and literature dat a in [4] demonstrates that the lattice structure spacing depends on such factors as loa- ding conditions (frequency, mechanical stress amplitude) and probably on the content of impurity elements (Mg). It is proposed [4] that 2D and 3D periodic lattices are formed due to self-organization of the defect structure of the mate- rial during cyclic tension and can be used in producing mi- croelectronic devices. The periodic stress and strain distribution under exter- nal influence on specimens, referred to as the chessboard- like effect, is found in studying surface layer  substrate interfaces [10, 11]. The authors explain the observed ef- fects by different characteristics of the weakened surface 85 P.V. Kuznetsov, I.V. Petrakova, Yu.G. Gordienko et al. / Physical Mesomechanics 12 12 (2009) 85`93