The comparative studies of Ni 50.8 Ti 49.2 wires and strips (processed using cold drawing and rolling, respectively) were carried out using microstructural and thermal characterization, X-ray studies and tensile tests. The <111> axial texture in drawn wires remains stable during subsequent post-deformation annealing (PDA) in the temperature range of 430–800 °C. The texture of the as-deformed strips is characterized by the predominance of the component {001} <110>. After PDA at 800 °C, the formation of the {111} <112> recrystallization texture is observed along with the persisting texture component {001} <110>. The texture exhibits a pronounced effect on the sequence of martensitic transformations in the temperature range of PDA at 430–600 °C. After PDA at 800 °C, the calorimetric curves of wires and strips become similar. Both kinds of samples were tensile tested in the temperature range of − 50 °C ≤ T ≤ + 50 °C. The transformation yield stress in strips is lower if compared to wires, this relation does not depend on the microstructure (or PDA mode). The effect of texture on strength characteristics as well as ductility is ambiguous: their ratio between wires and strips depends on microstructure which is determined by PDA mode. The observed regularities are analyzed using structural and textural analyses.

The crystallographic texture determines the anisotropy of zirconium alloys and is a sensitive indicator of all processes occurring in materials during plastic deformation, heat treatment, and operation. At present, the development of methods of scanning electron microscopy (SEM), as well as synchrotron radiation diffraction (SRD), makes it possible to significantly simplify the laborious procedure of texture analysis using the traditional X-ray diffraction method based on the results of the "reflection" survey. This work is devoted to the development of methods for quantitative X-ray texture analysis of deformed and annealed zirconium tubes using synchrotron radiation and the comparison of this data with the results obtained by the traditional X-ray texture analysis method. The results of texture analysis performed by different methods are compared. It is shown that when using the SEM and narrow beams of synchrotron radiation, the texture analysis is not very representative. Regularities are established for the improvement of the phase structure in deformed E110 and E635 alloys during annealing in the temperature range 480 - 640 degrees C, as well as some features of the SEM and SRD data. Regularities of recrystallization of the alpha-Zr-phase in the case of the presence of up to 1.6 wt.% of the beta-phase are revealed.

Based on the data of synchrotron and electron microscopic studies of deformed and annealed Russian zirconium alloys, the possibility of analyzing the structural-phase state and crystallographic texture of individual phases has been demonstrated. A qualitative and quantitative phase analysis of deformed and annealed tubes made of Zr-Nb-(Sn-Fe-O) alloys was carried out using diffraction patterns obtained with synchrotron radiation. The main α-Zr phase and the following additional phases: β-Nb, β-Zr, and the Laves phase (intermetallic compound Zr(Nb,Fe)2), were found in the alloys. According to the results of texture analysis of all phases present in the alloy, the mechanisms of plastic deformation, recrystallization, and phase transformations of the main and additional phases were established. It is shown that during plastic deformation of the Zr-1%Nb alloy, a dynamic phase transformation β-Nb→α-Zr→β-Zr is observed. It is established that during recrystallization, larger grains of α-Zr are misoriented relative to the deformed matrix by rotating the prismatic axes around the basal axes by 30°, while fine grains are improved by polygonization and maintain the orientation of the deformed matrix. Processes for changing the orientation of grains of additional phases as a result of high-temperature annealing are also considered.

Superelastic alloys based on Ti–Zr–Nb are low-modulus biocompatible alloys for medical applications. We analyzed the regularities of the development of martensitic transformations (MT) β (bcc) → α′′ (orthorhombic lattice) in Ti–(17–19)Zr–(14–15)Nb (at. 1 05)[501] in tension in the transverse direction.

This paper examines the processes of recrystallization in sheets of Zr – 2.5% Nb alloy rolled down to a 50–90% deformation and annealed at 610 oC for 1, 3 and 5 hours. The heating rate varied from 10 to 100 oC/min. With the help of X-ray structure and texture analysis, the authors looked at optimizing the crystal structure of the deformed alloy while examining changes in the crystallographic texture. It was established that annealing of Zr – 2.5% Nb alloy sheets performed at the temperature that corresponds to the dual phase region α + β of an equilibrium phase diagram also leads to recrystallization, as it happens when applying the annealing temperature of 580 oC. However, an 11% increase in the concentration of the additional phase suppresses changes in the crystallographic texture, which may be due to the predominant precipitation of β-zirconium at grain boundaries. At the same time, the growth of recrystallized grains still follows the main regularities of orientation: the orientation of growing grains corresponds to the texture maximum slopes of the direct pole figure (0001); an increased pole density was observed on the difference charts of the direct pole figure {10.0}, which is indicative of the presence of grains that are disoriented to the deformed matrix at 30o around the base normals. It is shown that the contribution of the above mentioned processes is determined by the type of initial texture, the annealing temperature, the heating rate and the amount of β-phase. An extended annealing time (from 1 to 5 hours) at the temperature of the dual phase region does not cause any significant change in the crystallographic texture.This research was funded by the Ministry of Science and Higher Education of the Russian Federation; Agreement No. 075-15-2021-1352.

Currently, low-modulus biocompatible Ti – Nb – Zr alloys are considered promising for medical applications. Superelasticity is a property that is mainly governed by the crystallographic direction in single crystals, i.e. by the predominant orientation of grains in polycrystalline objects. In order to control the crystallographic texture in products (such as foils), one should understand how it forms at various stages of thermomechanical processing. This paper compares the following alloys in terms of their crystallographic texture and how it forms: Ti –18Zr – 15Nb (18-15), Ti – 6Zr – 22Nb (22-6), Ti – 22Nb – (1–1.5)O (1O and 1.5O) (at.%). The composition of an alloy influences the stability of the initial β-phase, which tends to decrease with an increase in the concentration of Zr, which replaces Nb. A decreasing stability triggers martensitic transformations during rolling resulting in the formation of a weak blurry texture {112}<011>, as can be observed during deformation of alloy 18-15. Plastic deformation of a stable β-phase leads to the formation of a sharp twocomponent texture typical of BCC alloys: {110}<001> and {112}<011>, which develops during the rolling of alloys with oxygen and 22-6. Recrystallization of rolled foils (ε = 92%) at 650 оC for 0.5 h leads to sharpening of the texture components in the case of samples with a sharp deformation texture (22-6, 1O, 1 .5O) and to a change in texture in the case of samples with a weak deformation texture (18-15). Cyclic tensile tests conducted in three different directions revealed the presence of anisotropy in foils of all compositions. However, alloy 18-15 has the lowest anisotropy. An increase in the Zr concentration contributes to maximum reversible strain in the process of realizing superelasticity at room temperature. This research was funded by the Ministry of Science and Higher Education of the Russian Federation; Agreement No. 075-15-2021-1352.

The crystallographic aspects of the phase transformations in zirconium alloys under compressive stresses are studied, and the changes in the sizes of cladding tubes, rods, and rings made of E110opt and E125 alloys at compressive stresses and without them are determined. The temperature of the onset of the phase transformation on heating is found to shift toward low temperatures under a load applied to a cladding tube ring in the diametral direction, and a noticeable strain leading to the appearance of ellipticity of the rings are detected. Some of the versions of the Burgers orientation relationship are operative during the reverse β‒α phase transformation under compressive stresses, which manifests itself in the suppression of growth of texture maxima in the applied load direction during cooling. Deformation is shown to be accelerated on heating in the two-phase α + β region under compressive stresses, and the parameters of high-temperature creep are calculated using the temperature dependences of the strain.

The paper studies the regularities of the structure and texture formation in austenitic steel AISI 304 under cold rolling and subsequent heat treatment. Regularities of structure and texture formation depending on the roll-ing type and deformation degree were established. The ratios of main texture components, the volume fractions and the distortion of the martensite's crystalline lattice were analyzed. It is shown that mechanisms of the austenite-* martensite phase transformation in the course of cold rolling may change depending on various deformation schemes, as well as mechanisms of the reverse phase transformation variate under subsequent anneal-ing. Herewith depending on the rolling type and deformation degree, the crystallographic texture formation of the nucleating austenite under the heat treatment can have single component or multi-component character and follows different orientation relations. The more scattered martensite texture after deformation results in the formation of fine-dispersed austenite, which hardens the material keeping a sufficient level of plasticity.

As examples of austenitic steel 316L, nickel alloy (Inconel 625) and titanium alloy VT1-0, the regularities of the development of crystallographic texture in monolithic samples and lattice structures obtained by selective laser melting (SLM) of powder are considered. Crystallization of all of these alloys is carried out by the formation of crystals with a cubic structure {100} <001> (bcc or fcc). Upon subsequent cooling, the titanium samples additionally undergo a β→α phase transformation while maintaining the Burgers orientation relation. A sharp cubic texture {100}<001> is formed in the middle-height layers of a monolithic product, which determines the anisotropy of the properties of SLM samples. The layer-by-layer change in the crystallographic texture is associated with the growth of columnar crystals of the cubic phase, which are formed due to the thermal effect of the molten region on the underlying layers, which determine the orientation of the crystal during its crystallization. This texture is typical for both the fcc-phase of steel and the bcc-titanium phase. In the case of the formation of lattice structures, columnar crystals with a preferred orientation of <001> along the growth direction are formed in the central part of the ribs and nodes along the diameter of the structural elements. On the basis of the crystallographic texture of the steel lattice structures and the mechanical properties of the monolithic specimens, the strain curves of the lattices under their compression were calculated.

Currently, Ti-Zr-Nb-based biocompatible alloys are considered as prospective for medical applications. In this work, the mechanisms of the formation of the crystallographic texture of five alloys Ti-(17-19)Zr-(14-16)Nb (at.%) have been compared. The presence of martensitic transformations during the rolling process determines the features of the formed texture. At the initial stage of deformation (ε = 50%), the texture {112}<011> is formed in all five alloys. With an increase of the degree of deformation to 92%, the texture dissipates somewhat, which is due to an increase in the fraction of the martensitic phase in the foils. Recrystallization of rolled foils (ε = 92%) at 650°C leads to an exacerbation of the texture component close to {100}<011>, the blurring of which varies in different alloys. Cyclic tensile tests along three directions: the rolling direction (RD), the transverse direction, at an angle of 45° to the RD showed the presence of anisotropy in the samples. It was shown, that the effect of superelasticity is orientation-and structure-depending, and the anisotropy of mechanical properties.

Zirconium remains the main structural material for thermal reactors due to the small capture cross section of thermal neutrons. In the period of stricter safety requirements for reactors with a simultaneous increase in operating parameters, predicting the behavior of the material in emergency situations has gained greater urgency. In this work, we measured the temperature dependence of the thermal expansion of samples cut from thick-walled tubes made of Zr-2.5% Nb alloy that were deformed and annealed in different modes. The analysis of the physical processes responsible for the shaping of the material is carried out. It was found that the anisotropic change in the linear dimensions of cubic samples both during heating and cooling is due to a change in the zirconium content in the β-phase, phase transformations α + β-Zr → α + β-Nb → β → α + β-Zr, as well as the preferred orientation of the grains of the α-phase, characterized by high anisotropy of linear expansion. It is shown that the expansion of the investigated samples upon heating in the α -phase is determined exclusively by the integral texture parameters of Kearns, and the coefficients of thermal linear expansion (TLEC) in different directions vary over a wide range from 3⋅10-6 to 12⋅10-6 K−1. During cooling at the stage of the reverse phase transformation of the β-phase into α, an increase in the size of the cubic samples in the tangential direction up to 2.3 % and a decrease in the radial direction to 1.3 % are noted, which is associated with the orientation of the α-phase grains formed during cooling in the β -matrix and anisotropy of the TLEC of the α -grains. It is shown that the orientation of the α-phase grains in the reverse β → α transformation is determined not only by the orientation of the basal axes in the initial material, but also by the spatial distribution of the prismatic axes relative to the external directions in the tube. Significant size fluctuations in different directions of the samples obtained using the technology of manufacturing channel tubes for CANDU reactors should lead to the development of significant macrostresses both during heating and cooling of the tube. The structural state of the samples deformed or annealed at 400–530 °C does not significantly affect the temperature dependence of the TLEC, but is manifested only in some of its features. In this case, completely recrystallized samples, i.e., with a recrystallization texture, in which the < 112-0 > directions are oriented along the tube axis, are characterized by a significantly lower variation in dimensions in different directions in the temperature range 20–1200 °C.

The experimental results to the effect of irradiating conditions by intense pulsed electron beams on texture and residual stresses formation in the surface layer of targets from VT8 titanium alloy are analyzed. These data have great practical significance because the blades and disks of VK-2500 helicopter engine compressors are produced from this material. The information on texture formation and residual stresses in the surface layer allows to determine service properties (fatigue resistance and heat-resistance) of parts from this material. It is shown that intense pulsed electron beam of microsecond duration is high effective tool for modification of compressor and turbine blades from VT8 alloy. It allow to realize high speed heat treatment (hardening), recrystallization of material in the surface layer with thicknesses of 20...30 µm, purification and burnishing of surface. It is possible to form in the surface layer tensile or compressive residual stresses and compressive or tensile textures depending upon energy density in pulse in the surface layer of VT8 targets. Compressive residual stresses are formed during irradiation at low energy density in pulse (lesser 20 J/cm2 ). Microdefects with craters form are not formed at these irradiation regimes that is absence of stress concentrates.

Any material can be considered a composite consisting of grains of different orientations which possess different properties depending on the history of their reorientation upon thermomechanical processing. A well-known selective character of X-ray methods is attributed to the fact that only grains of certain orientations participate in the formation of reflected radiation. A comprehensive description of the material including information about the substructure of grains of all orientations necessitates developing of the method providing description of the substructural state of grains located in the volume under study by analyzing the profile of x-ray lines. The proposed x-ray diffractometric method of Generalized Direct Pole Figures (GPF) which suggests combination of texture imaging and recording the profile of x-ray lines appeared to be rather efficient in a systematic x-ray study of the substructural heterogeneity of textured metallic materials. The measured parameters of the X-ray line profile — the true angular half-width β and angular peak position 2θ — are determined by the distortion (fragmentation) of the reflecting grains and interplanar spacings in their crystal lattice, respectively. The method provides a possibility to compare the substructure features of grains with different crystallographic orientations. An algorithm for calculation of the true physical half-width of the x-ray line using the necessary computer programs is presented. GPF β and GPF 2θ are presented for metal materials with hcp, fcc, and bcc crystalline lattices, as well as characteristic diagrams of their mutual correlation with texture PF. The use of the developed GPF method makes it possible to identify patterns of the formation of substructural heterogeneity during plastic deformation of metals.

Influence of various deformation regimes, included severe plastic deformation by multi-pass rolling, rotary forging and equal channel angular pressing (ECAP) in the normal and quasi-continuous modes, on the structure and properties of Ti-Ni shape memory alloys was studied and compared. Features of structure formation providing a combination of high functional properties were analyzed. Investigation of the texture development, depending on the ECAP regimes and post-deformation annealing, was made.

This paper is devoted to the regularities of change in the crystallographic texture and the structure of cladding tubes with a total degree of deformation by their cross-section of 70-80% as a result of polygonization or recrystallization during heat treatment in the temperature range from 480 to 600 °C. It is shown, that there are two competing processes of crystal lattice perfection in cladding tubes at annealing temperatures over 540 °C. The oriented growth of grain nuclei, formed at the boundaries of grains and disoriented with respect to the deformed matrix by an angle of 20-30° about basal axes, is predominant. At the recrystallization of cladding tubes from E110 alloy, a significant change in their crystallographic texture of cold rolling is observed, i.e. an increase of the integral texture parameter fr increases, and a decrease of fT. The grains, formed at the stage of plastic deformation by twinning, prove to be unstable even at the stage of polygonization, due to the mobility of highly disoriented boundaries under conditions of the anisotropic thermal expansion of neighboring regions.

The present paper reviews the experimental results dedicated by the effect of the irradiation with high-current pulsed electron beams under the melting regime on residual stresses creation taking place on the surface of titanium alloy targets (VT6, VT8, VT9, VT18U). Investigations of physical and chemical state in the surface layers before and after irradiation were made with the transmission electron microscopy, optical metallography, X-rays analysis and microhardness measurements. It was showed that irradiation with high-current pulsed electron beams under the melting stage of VT6 and VT8 alloys leads to formation the stress texture into the surface layer with thickness up to 20 μm. Irradiation of VT9 and VT18U alloy targets with 18-45 J/cm2 leads to formation of tensile residual stresses. It effects on the fatigue strength of titanium alloy parts.