In this paper, we analyze effects of hot rolling on the shape, structure, texture, and properties of a Ti–4.5Al–3Mo–V alloy (VT14) titanium alloy. The phase composition, texture, and morphology of the formed phases in the initial state and after rolling are determined. The effect of the deformation degree between the passes on the formation of various components of the deformation texture and recrystallization is shown. The dependence of VT14 alloy widening during flattening under the action of hot deformation in one pass are analyzed. A decrease in the widening coefficient at a similar degree of deformation is noted. Relationships between the studied hot deformation routes, the α/β-phase ratio, the morphology of the secondary α phase, the development of recrystallization in the β phase, as well as the hardness and contact elasticity modulus of VT14 alloy were determined.

The effect of alloying of model alloys based on a Ti – 10Al binary alloy with additives of 1

Методами дифференциальной сканирующей калориметрии, растровой электронной микроскопии, микрорентгеноспектрального и рентгеноструктурного фазовых анализов, микроиндентирования изучено влияние термического воздействия на структурно-фазовое состояние и физико-механические свойства сплава на основе орторомбического алюминида титана (О-сплава), полученного селективным лазерным сплавлением. Изменение режима селективного лазерного сплавления, а именно повышение величины относительной плотности энергии при синтезе с 49 до 97 Дж/мм3 приводит к эволюции характера пористости образцов после селективного лазерного сплавления: от пористости, связанной с непроплавом частиц порошка, к газовой пористости, наследуемой от пор в порошке. Фиксируемый в О-сплаве при селективного лазерного сплавления метастабильный β-твердый раствор при нагреве со скоростью 50 К/мин до 900 °С претерпевает распад в двух диапазонах температур 300–600 и 650–800 °С. Повышение температуры термообработки с 750 до 900 °С синтезированного О-сплава способствует уменьшению объемной доли и укрупнению размеров О-пластин, выделяющихся при распаде β-твердого раствора, что приводит к уменьшению эффекта дисперсионного упрочнения (роста твердости) и прироста модуля упругости. Рассмотрено влияние величины относительной плотности энергии при селективном лазерном сплавлении на химический состав синтезируемого О-сплава, стабильность фиксируемого β-твердого раствора к процессам распада и формируемый комплекс физико-механических свойств при термообработке. Using the methods of differential scanning calorimetry, scanning electron microscopy, micro-X-ray spectral and X-ray structural phase analysis, microindentation, the influence of thermal effects on the structural-phase state and physical and mechanical properties of an alloy based on orthorhombic titanium aluminide (O-alloy), obtained by selective laser melting, was studied. A change in the selective laser melting regime, namely an increase in the relative energy density during synthesis from 49 to 97 J/mm3 leads to an evolution of the nature of the porosity of samples after selective laser melting from porosity associated with non-melting of powder particles to gas porosity inherited from pores in the powder. The metastable β-solid solution fixed in the O-alloy during selective laser melting, when heated at a rate of 50 K/min to 900 °C, undergoes decomposition in two temperature ranges 300–550 and 700–800 °C. Increasing the heat treatment temperature from 750 to 900 °C of the synthesized O-alloy promotes reduce the volume fraction and the enlargement of O-plates released during the decomposition of the β-solid solution, which leads to a decrease in the effect of dispersion strengthening (hardness growth) and an increase in the elastic modulus. The influence of the relative energy density value during selective laser melting on the chemical composition of the synthesized O-alloy, the stability of the fixed β-solid solution to decomposition processes, and the complex of physical and mechanical properties formed during heat treatment is considered.

Electrode induction gas atomization (EIGA) is a perspective, cost-effective method for producing spherical intermetallic titanium powders used in additive manufacturing. This study investigates the morphology, microstructure, nanoindentation properties, chemical and phase composition of commercial pre -alloyed EIGA powder of the Ti 2 AlNb-based alloy. The effect of particle size distribution on flowability is studied. Ti-23Al-25Nb powder is characterized by a typical dendritic single beta-phase microstructure with almost homogeneous distribution of alloying elements. The dendriti & scy; body is slightly enriched with Nb and the dendritic boundaries are enriched with Al. The temperature ranges of phase transformations are studied using differential scanning calorimetry at a rate of 50 degrees / min. Several phase transformations including beta -iota omega 0 ; beta -iota O; O -iota beta+alpha 2 ; alpha 2 -iota beta are revealed during heating. The activation of the powder oxidation process at temperatures above 700 degrees C is observed.

Abstract—The methods of scanning electron microscopy, X-ray diffraction analysis, and microindentation are used to study the effect of alloying with zirconium (within 3 to 6 at H^3/ . -0emE_r^2 (Н is the hardness and Er is the resolved modulus of elasticity) associated with the wear resistance as compared to those for the widely used medical Ti–6Al–4V alloy. The compositions of the alloys and conditions of their treatment are determined, which allow us to obtain the combination of the highest-level properties.

This article presents the results of the modeling of the behavior of the titanium alloy Ti-3Al‑2.5V at the initial stage of extrusion of a tube billet. The influence of the gaps between the surfaces of the tool and the billet on the nature of its shape change and the strain state is discussed. In particular, the most deformed tube parts of the maximum (by modulus) strain tensor values are identified. The dependence of the Ti-3Al‑2.5V alloy tube extrusion force on the stroke of the pressure pad is calculated. The results of the calculation of the maximum forces and the forces at the steady-state stage are in good agreement with the data obtained under an industrial experiment. Horizontal extrusion leads to an asymmetry in the location of the deformation fields relative to the extrusion axis. Accordingly, an asymmetric distribution of properties arises in the extruded tube, which is experimentally confirmed using hardness measurements. Correspondence is established between the simulation data on the heterogeneity of the strain distribution over the wall thickness of the hot-pressed tube made of titanium alloy Ti-3Al‑2.5V, considering the pressing-out, with the results of micro- and X‑ray structural studies of the tube semifinished product obtained.

The impact of selective laser melting (SLM) process parameters on the porosity, microstructure, phase and chemical composition, texture, and physical-mechanical properties of orthorhombic titanium aluminide Ti2AlNb (O-alloy) powder was studied using a range of methods, including hydrostatic weighing, scanning and transmission electron microscopy, X‑ray diffraction analysis, energy-dispersive X‑ray spectroscopy, microindentation, and compression testing. It was demonstrated that an increase in the volumetric energy density within the range of 28 to 139 J/mm3 led to the following effects: 1) increase in the relative density of the obtained O‑alloy from 97 to 99.9

Abstract—Differential thermal analysis, scanning electron microscopy, X-ray diffraction analysis, and microindentation are used to study changes in the structure, phase composition, microhardness, and contact modulus of elasticity of a heat-resistant alloy based on the Ti2AlNb titanium intermetallic compound, depending on the rate of colling (10–80°/min) from heating temperatures of 950 and 970°С. Using the results obtained, thermokinetic diagrams of high-temperature decomposition of the β(B2) solid solution are constructed.

Electrode-induction gas atomization (EIGA) is a promising and cost-effective method for producing spherical intermetallic titanium powders used in additive manufacturing. The present study investigates the morphology, microstructure, chemical and phase compositions, nanoindentation properties of a commercial pre-alloyed TiAl-based EIGA alloy powder. The Ti – 48Al – 2Cr – 2Nb powder is characterized by a spherical shape and dendritic structure with the dendrites enriched with Nb and the interdendritic areas enriched with aluminum and chromium. The temperature ranges of the phase transformations in the powder with precipitation/dissolution of phases α2 , α, γ, B2, (TiNb)Cr2 are determined using thermal analysis during heating and cooling in an inert atmosphere of argon at a rate of 50 K/min. Development of an oxidation process at the temperatures above 500°C and significant increase in its rate at the temperatures above 900°C is detected.

The evolution of microstructure, phase composition and physico-mechanical properties of the biocompatible Ti-39Nb-7Zr alloy (wt.%) after severe plastic deformation by rotary forging (RF) was studied using various methods including light optical microscopy, scanning and transmission electron microscopies, X-ray diffraction, microindentation, tensile testing and investigation of thermophysical properties during continuous heating. The hot-rolled Ti-39Nb-7Zr with initial single β-phase structure is subjected to multi-pass RF at 450 °C with an accumulated degree of true deformation of 1.2, resulting in the formation of a fibrous β-grain structure with imperfect 500 nm subgrains characterized by an increased dislocation density. Additionally, nano-sized α-precipitates formed in the body and along the β-grain boundaries. These structural changes resulted in an increase in microhardness from 215 HV to 280 HV and contact modulus of elasticity from 70 GPa to 76 GPa. The combination of strength and ductility of Ti-39Nb-7Zr after RF approaches that of the widely used Ti-6Al-4V ELI alloy in medicine, however, Ti-39Nb-7Zr does not contain elements with limited biocompatibility and has a modulus of elasticity 1.5 times lower than Ti-6Al-4V ELI. The temperature dependences of physical properties (elastic modulus, heat capacity, thermal diffusivity) of the Ti-39Nb-7Zr alloy after RF are considered and sufficient thermal stability of the alloy up to 450 °C is demonstrated.

В статье проведен анализ влияния режима горячей прокатки на формоизменение, структурно-текстурное состояние и свойства титанового сплава ВТ14. Определен фазовый состав, текстура и морфология образующихся фаз в исходном состоянии и после прокатки по различным маршрутам. Показано влияние степени деформации между проходами на формирование различных компонент текстуры деформации и рекристаллизации. Проанализированы зависимости уширения при плющении от относительного обжатия при горячей деформации сплава ВТ14 в проходе. Отмечено уменьшение коэффициента уширения при близкой степени деформации с увеличением номера прохода. Определена взаимосвязь между влиянием исследованных режимов горячей деформации на соотношение количества α/β-фаз, дисперсность вторичной α-фазы в структуре, развитие процессов рекристаллизации в β-фазе и фиксируемым в сплаве ВТ14 уровнем твердости и контактного модуля упругости. The article analyzed the influence of hot rolling on the shape change, structure and texture and properties of the titanium Ti–4,5Al–3Mo–V (VT-14) alloy. The phase composition, texture and morphology of the phases in the initial state and after rolling were determined. The influence of the degree of deformation between passes on the formation of various components of the deformation texture and recrystallization is shown. The dependences of spreading during flattening during hot deformation of the VT14 alloy in a pass are analyzed. A decrease in the spread ratio at a similar degree of deformation was noted. The relationships between the hot deformation routes, the α/β phase ratio, the morphology of the secondary α phase, the development of recrystallization in the β-phase, and the hardness and contact elasticity modulus of the VT14 alloy were determined.

In situ X-ray diffraction studies of a hardened Ti–26 at

Исследованы морфология, микроструктура, химический и фазовый составы, свойства после наноиндентирования порошка промышленного сплава Ti – 48Al – 2Cr – 2Nb на основе алюминида титана TiAl, полученного методом электродно-индукционного газового распыления (EIGA). Установлено, что порошок характеризуется сферической формой частиц и дендритной структурой, обогащенной ниобием, а междендритные участки обогощены алюминием и хромом. Методом термического анализа при нагреве в инертной атмосфере аргона со скоростью 50 °C/мин определены температурные интервалы реализации в порошке фазовых превращений с выделением/растворением фаз — α2, α, γ, B2, (TiNb)Cr2. Установлено развитие процесса окисления порошка при нагреве выше 500 °C и существенное повышение скорости окисления при температурах выше 900 °C.

Методами световой микроскопии, рентгеноструктурного фазового анализа, микроиндентирования, термодинамических расчетов в ThermoCalc изучено изменение структуры, фазового состава, химического состава фаз, микротвердости по Виккерсу, контактного модуля упругости в высокопрочном титановом α + β-сплаве мартенситного класса VST2 при закалке от температур нагрева в диапазоне 700 – 1000 °C. Показана хорошая сходимость экспериментальных данных и термодинамических расчетов. Установлена взаимосвязь характера изменения микротвердости и контактного модуля упругости в сплаве VST2, закаленном от 700 – 1000 °C, с эволюцией структуры и фазового состава при закалке.

Методами гидростатического взвешивания, растровой и просвечивающей электронной микроскопии, рентгеноструктурного и микрорентгеноспектрального анализов, микроиндентирования, испытания на сжатие изучено влияние режима селективного лазерного сплавления (СЛС) порошка сплава на основе орторомбического алюминида титана Ti2AlNb (О-сплава) на пористость, структурно-фазовое состояние, химический состав, текстуру и физико-механические свойства получаемых образцов. Показано, что увеличение используемой в работе при синтезе объемной плотности энергии в диапазоне от 28 до 139 Дж/мм3 способствует: 1) повышению относительной плотности получаемого О-сплава с 97 до 99,9%, 2) усилению аксиальной текстуры с выраженным направлением 001 в фиксируемом β/B2-твердом растворе, 3) снижению содержания алюминия, повышению содержания ниобия в сплаве и менее значительному его обогащению кислородом. Обнаружено, что отделение от платформы построения и разрезка О-сплава в продольном сечении приводит к нарушению баланса остаточных напряжений в образцах, синтезированных на нагретой до 200 °С подложки, с образованием в них трещин. Выявлены характерные дефекты структуры сплава (поры, непроплавы, химическая неоднородность) после сплавления порошка. Определен комплекс физико-механических свойств, синтезированных О-сплавов (твердость – 390–430 НV, контактный модуль упругости – 91–98 ГПа, предел текучести при сжатии – 1060–1080 МПа, относительное укорочение при сжатии не менее 30%. Рассмотрена связь получаемого уровня свойств в О-сплаве с формируемым при синтезе структурно-текстурным состоянием. The influence of the of selective laser melting (SLM) process parameters of the alloy based on orthorhombic titanium aluminide Ti2AlNb (O-alloy) on porosity, microstructure, phase and chemical compositions, texture, physical and mechanical properties using the methods of hydrostatic weighing, scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy, microindentation and compression testing were studied. It was demonstrated that the increase in the SLM in the range of volumetric energy density from 28 J/mm3 to 139 J/mm3 contributes to: 1) the increase in the relative density of the resulting O-alloy coupons from 97 to 99.9%, 2) the intensification of the solidification <001>-fiber texture of β/B2-solid solution, 3) decrease in Al, increase in Nb content and lesser enrichment with oxygen in the as-built coupons. The separation the O-alloy from the platform and along the building direction results in the imbalance of residual stresses accompanied by the crack formation in samples fused on a substrate preheated at 200°C. The typical defects (pores, lack of fusion, chemical inhomogeneity) after SLM are discussed. A combination of physical and mechanical properties of the synthesized O-alloys coupons was determined (Vickers microhardness - 390...430 HV, contact modulus of elasticity – 91–98 GPa, compressive yield strength 1060–1080 MPa, relative shortening in compression of at least 30%. The relationship between the resulting level of properties and a microstructure-texture in an O-alloy state formed of as-built SLM samples are considered.

The article provides systematization and comparative analysis of data for structure, phase composition, physical and mechanical properties formed within deformed pipes of semifinished products in different stages of preparing cold rolled pipes from hot-rolled pipe billets of titanium alloys PT–1M, PT–7M, Ti–3Al–2.5V. The effect of the degree of cold deformation on strain hardening of specimens from alloy hot-extruded pipes of semifinished products of the test alloys is established and on the basis of this recommendations are developed for maximum acceptable degree of deformation during cold rolling of pipes made of PT–1M, PT–7M, Ti–3Al–2.5V alloys. Deformation warming of alloys during cold rolling is evaluated. It is shown that cold rolling of pipes of the alloys studied into intermediate and final pipe workpieces with the reduction recommended contributes to the pipe strain hardening. When simulating cold rolling of pipes calculation of the Q- factor is carried out, which has a value of about 1. Cold rolling with such a value of Q- factor leads to formation of a texture of an inclined tangential prism alloying alloy from PT–1M to Ti–3Al–2.5V. It is noted that intermediate and final annealing at 680°C (PT–1M alloy), 750°C (PT–7M alloy, Ti–3Al–2.5V) of cold-rolled pipe billets studied facilitates alloy loss of strength as a result of occurrence of recrystallization and to the formation of a two-component texture {0001}±φ°TD<10–10>RD and {0001}±φ°TD<11–20>RD. Features of structure formation, phase composition, and mechanical properties of pipes in relation to alloying are considered.

The impact of heat treatment on the structural-phase characteristics, physical and mechanical properties of an alloy based on orthorhombic titanium aluminide (O-alloy) produced by selective laser melting was investigated using differential scanning calorimetry, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis, and microindentation. Modifying the selective laser melting process parameters, specifically increasing the relative energy density from 49 to 97 J/mm3, results in the evolution of the porosity character of the samples after selective laser fusion. This transition is observed from porosity associated with the lack-of-fusion to the gas porosity inherited from the pores in the powder and gas entrapment during melting. The metastable β‑solid solution that is fixed in the O‑alloy during selective laser melting undergoes decomposition in two temperature ranges, 300–600 °C and 650–800 °C, when heated at a rate of 50 °C per minute up to 900 °C. An increase in the heat treatment temperature from 750 to 900 °C of the as-built O‑alloy results in a reduction in the volume fraction and an expansion in the thickness of the O‑platelets precipitated during the decomposition of the β‑solid solution. This phenomenon leads to a decline in the impact of dispersion hardening (hardness growth) and enhancement in the elastic modulus. This study examines the impact of volumetric energy density during selective laser melting on the chemical composition of the O‑alloy, the stability of as-built alloy to decomposition of β‑solid solution and the formation of a combination of physical and mechanical properties during heat treatment.

In situ X-ray diffraction studies of a hardened Ti-26 at % Nb alloy with an initial single-phase beta structure sublected to tension allows studying the processes occurring upon application of deformation and correlating them to three intervals of strain values. The first range of values (up to 0.7%) is the region of elastic deformation of the bcc lattice of the beta titanium solid solution. In the second interval (0.7-1.4%), the occurrence of the strain-induced beta -> tau transformation is recorded, and, as the strain increases to 1.4%, an increase in the c/a parameter of this lattice is observed. In the third strain range (1.4-2.2%), plastic deformation of the beta and tau phases occurs. The resulting tau phase after the test remains quite stable. It is found that after tensile tests, the Young modulus of the hardened Ti-26Nb alloy decreases from 58 to 52-54 GPa, and the microhardness increases from 200 to 240 HV.