Papers by Keyword: Generalized Pole Figure

Abstract: The X-ray method of Generalized Pole Figures was used by study of residual deformation effects in steel shell tubes for high-temperature atomic reactor. Ferritic-martensitic steel contained disperse strengthening oxide particles and their behavior under technological treatment was of essential practical interest. The used procedure estimates residual deformation effects in grains with different orientations and depicts distributions of elastic lattice distortion and interplanar spacings. Invisible oxide particles redistribute within the tube wall and strain hardening at its outer side is higher.

Abstract: Typical modes of the microstress distribution were found by X-ray study of Ti-Ni rolled single crystals using the X-ray method of Generalized Pole Figures. The method consists in successive measurements of the peak position 2θ for the same X-ray line of B2 phase by all possible positions of the sample in the course of diffractometric study of its texture. In the case of one-component rolling texture maxima in pole figure break into halves with opposite signs of elastic deformation, whereas by two-component rolling textures the one-sign elastic strain dominates within different maxima.

Abstract: Abstract. Experimental evidences of regular differences in the substructure condition of grains depending on their position within texture maxima are demonstrated. Analysis of generalized pole figures (GPF) for rolled metal materials shows that the strain hardening intensifies as an angular distance of grains from the texture maximum centre increases. The mechanisms of this phenomenon are considered using the concepts of the texture formation theory.

Abstract: Abstract. Anisotropy of physical and mechanical properties of textured polycrystalline materials strongly depends on microstructural characteristics, such as subgrain sizes, lattice deformations, etc. Generalized Pole Figures (GPF) are an attempt to estimate the anisotropy of these properties; so, the energy stored during plastic deformation is a key parameter in primary recrystallization. In this work, the technique to measure GPF (measurements and software) was implemented for X-Ray diffraction and applied to study of property anisotropy of a Fe50%Ni alloy. GPF’s of texture, crystallite size, stored energy and diffraction peak shift, (among others) have been characterized. The Full Width at Half Maximum (FWHM) of obtained instrumental functions shows that defocusing is significant for polar angle higher than 50°. The mixing parameter of the pseudo-Voigt function using in fitting, presents important dispersions.

Abstract: For systematic study of the distribution of residual deformation effects in textured metal materials the method of Generalized Pole Figures was developed, combining texture measurement with X-ray line profile measurements in such a manner that the profile of the same X-ray line (hkl) is registered by each successive position of the sample. The obtained totality of profiles after that or another treatment is used for construction of Generalized Pole Figures (GPF), i.e. distributions of measured diffraction parameters or calculated substructure parameters in the stereographic projection of the sample depending on the orientation of reflecting crystallographic planes. As applied to metal materials with developed rolling textures it was found that any volume ~1 mm3 is characterized by an extremely wide spectrum of substructure conditions. Three laws of substructure anisotropy were revealed for the first time. The 1st law: Residual deformation effects are minimal along directions, corresponding to maximal density of crystallographic axes, i.e. texture maxima, and increase up to highest values by passing to texture minima. The 2nd law concerns variation of lattice parameters in metal products due to elastic microstrain: For each grain with crystalline lattice, extended along axis by (+ε), there is its pair with the symmetric orientation, where along axis crystalline lattice is compressed by (-ε), so that accompanying elastic microstresses are equilibrated. The 3rd law: By passing from residual tension of the crystalline lattice to its compression, grain fragmentation changes depending on indexes of the reference axis, i.e. tensile and compressive elastic deformations of the crystalline lattice differ in their uniformity.

Abstract: Possibilities of X-ray methods, using diffractometric measurements of X-ray line profiles and crystallographic texture, are compared as applied to study of SPD metal materials. The texture analysis gives the most direct data on the degree of grain fragmentation under conditions of deformation. The consideration is illustrated by results, obtained by X-ray studies of ECAP rods from Cu and Ti.

Abstract: By taking into account an interconnection between substructure non-uniformity and substructure anisotropy, a new approach to study the substructure non-uniformity is developed as applied to metal rods, subjected to Equal-Channel Angular Pressing (ECAP). The X-ray method of Generalized Pole Figures (GPF) was used for construction of distributions of substructure parameters. Some experimental data are presented, illustrating possibilities and efficiency of the used approach.

Abstract: The substructure inhomogeneity of real textured metal materials was studied by use of the X-ray method of Generalized Pole Figures. Main regularities of substructure inhomogeneity were revealed for the first time. Substructure conditions of grains in rolled material form an extremely wide spectrum and vary by passing from texture maxima to texture minima, where residual deformation effects are most significant. The distribution of residual elastic microstrains in the orientational space of rolled material shows the distinct cross-wise system, consisting in alternation of quadrants with predominant microstrains of opposite signes.

Abstract: A detailed X-ray study of Zr rods, subjected to ECAP at 350oC by routes C and BC, was conducted by the new X-ray method of Generalized Pole Figures, combining texture measurement with registration of X-ray line profiles. The data analysis is based on conceptions of the texture formation theory, connecting features of grain reorientation with activated deformation mechanisms. A degree of reproduction of the same distinctive texture by successive ECAP passes with antecedent rotation of the rod reflects attendant structure changes in material.

Abstract: The substructure nonuniformity of metal materials with developed deformation texture was studied by use of the X-ray method of Generalized Pole Figures. Main regularities of substructure nonuniformity were revealed for the first time. Substructure conditions of grains in rolled material form an extremely wide spectrum and vary by passing from texture maxima to texture minima, where residual deformation effects are most significant. The distribution of residual elastic microstrains in the orientational space of rolled material shows the distinct cross-wise system, consisting in alternation of quadrants with predominant microstrains of opposite signs.