Papers by Author: D.I. Nikolayev

Abstract: Equal channel angular pressing (ECAP) was used for grain refinement and texture modification in the initial pressed Mg-Al-Zn alloy to study the possibility to enhance the low-temperature deformability of the material. The effect of different ECAP regimes by routes A, C, and BC on the submicrocrystalline grain formation, texture evolution, and plasticity of the alloy have been investigated. The ECAP of the alloy results in the formation of ultrafine grained structure with a grain size of 0.8-3.5 µm independent of pressing routes and regimes. The ECAP also drastically changes the axial texture by splitting the initial texture characterized by a sharp basal component to several more scattered orientations. The degree of the orientation scattering depends on the ECAP regime and route. It is proposed to estimate the effect of the texture on the yield strength and plasticity of the alloy after ECAP through generalized Schmid factors. The comparable calculated and experimental results are obtained only for yield strength.

Abstract: The objective of the present work is to study of errors on measured pole figures of hexagonal materials. We used neutron time-of-flight (TOF) technique for texture measurements and obtained spectra for estimating of error values of measured pole figures. Peak profile analysis of an each individual spectrum allows gain pole figure value itself and the corresponding error at each pole figure point as well. Such results could be obtained for measurements on stationary source of radiation with the usage of a position sensitive detector.

Abstract: Method to process neutron time of flight spectra for extracting texture information is suggested. Local peak fit is used to gain integral peak intensities as well as errors of fitted peak parameters. The usage of the method illustrated on spectra collected for Mg sample measured at Dubna on IBR-2 pulsed reactor at SKAT texture diffractometer. Reconstructed pole figures and corresponding errors are presented and discussed. It is important to underline that obtained errors are independent of the further method of pole figure processing.