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Laws of substructure anisotropy of textured metal materials

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Any metal material with a developed crystallographic texture shows the substructure anisotropy, i.e. different values of substructure parameters, measured along different directions. Usually such measurements are realizable by methods of X-ray diffractometry. Among substructure parameters, influencing the pattern of X-ray diffraction and, in particular, profiles of X-ray lines, there are interplanar spacings of the crystalline lattice, coherent domain size, lattice distortion, dislocation density. However, it is evident for specialists in X-ray analysis, that the above simplest definition of substructure anisotropy needs an additional clarification concerning the term “different directions". Since all X-ray measurements of substructure parameters use concrete X-ray lines (hkl), which are reflections from the corresponding crystallographic planes {hkl}, these measurements characterize the substructure as it is seen only along crystallographic axes . Therefore, the definition of substructure anisotropy as applied to a textured polycrystal means, that we compare substructure parameters, measured along crystallographic axes of the same type parallel to different directions (ψ, φ) in the system of external coordinates. In the particular case these axes can belong to the same grain, then measured substructure parameters characterize the substructure anisotropy, developed in grains with a concrete orientation under deformation. When considering the substructure anisotropy of material, references to orientations (ψ, φ)i of axis are sufficient for its characterization, whereas the description of substructure non-uniformity of textured material requires to split the distribution of axes into sets, belonging to grains with different orientations, characterized with Euler angles. At the same time the concept of substructure anisotropy is close to the concept of substructure non-uniformity in [...]

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