Study of the anisotropy of the polycrystal properties based on texture data

Abstract

The results of studying correlation between the crystallographic texture of polycrystalline materials and anisotropy of their physical and mechanical properties are considered. The methods for calculating the anisotropic properties of polycrystals based on the data obtained by X-ray methods of direct and inverse pole figures are reviewed. Calculation methods based on the use of the distribution function of crystallite orientations require the use of a large amount of experimental data and, hence, they are not suitable for express estimation of the anisotropy level of the physical properties of samples upon their thermomechanical processing. A method for rapid estimation of the anisotropic properties of the sample based on the use of Д; ("orientation factors") in the calculations, is proposed. Experimental data of X-ray analysis (method of inverse pole figures) are used to calculate the absolute and relative deviations of the physical parameter of textured polycrystal from the same value in the isotropic sample. The contributions of individual crystallographic orientations to the formation of the anisotropy of the properties of the sample are estimated. The dynamics of quantitative changes in the anisotropic properties of a polycrystal in the process of texture formation is studied. To analyze the source of the most rapid changes in the anisotropy of properties, we used the coefficients of the "response" matrix, the calculation of which does not depend on the results of specific diffractometric measurements, but is common for all metals with a hexagonal close-packed (hep) lattice. The anisotropy of the coefficient of thermal conductivity, electrical conductivity, and thermal diffusivity was calculated for the samples of deformed yttrium which underwent cold rolling with a reduction ratio of e = 25%. It is shown that the final physical properties_of the hep polycrystal are largely determined by the pyramidal crystallographic orientations {1015}, {1124}. The results of the study form a basis for analysis of the anisotropy of the physical properties of hep-metal samples upon thermomechanical processing.