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The present paper is a brief review of superplastic behavior of intermetallic alloys based on γ-TiAl + α 2 -Ti 3 Al with varying niobium content and refined microstructure obtained by hot working. Three γ + α 2 alloys having the nominal compositions Ti-44.2Al-1.9Cr-0.7Nb-0.4B, Ti-45Al-8Nb-0.2C and Ti-43.7Al-4.2Nb-0.5Mo-0.2B-0.2C (at. %) are considered in the paper. The hot working included quasi-isothermal hot forging or extrusion in the α + γ or α + β (B2) + γ phase field and hot forging at T = 950°C. The hot working led to formation of refined partially rectystallized / globularized microstructures in the Ti-44.2Al-1.9Cr-0.7Nb-0.4B and Ti-43.7Al-4.2Nb-0.5Mo-0.2B-0.2C alloys and fully ultrafine grained microstructure in the Ti-45Al-8Nb-0.2C alloy. The fine grained materials were used to prepare specimens for tensile testing. The tensile tests were performed at T = 800 -1000°C and έ ~ 10 −4 -10 −3 s −1 in air without any protection against oxidation. Superplastic elongations and higher values of the strain rate sensitivity coefficient (m > 0.3) were reached at T = 850 -1000°C for all alloys under study. The comparison of the superplastic properties of the alloys suggests that superplastic elongations were significantly higher owing to more intensive hot working and in the alloys with higher niobium content and volume fraction of the α 2 phase. Microstructure examination showed that the last two factors provided slow dynamic grain growth during superplastic flow leading to sustainable superplastic flow and superior superplastic elongations (δ > 1000 %) in the Ti-43.7Al-4.2Nb-0.5Mo-0.2B-0.2C and Ti-45Al-8Nb-0.2C alloys. Particularly, incredible high superplastic elongations (δ = 1270 -2860 %) were attained in the Ti-43.7Al-4.2Nb-0.5Mo-0.2B-0.2C alloy at T = 900 -1000°C. The obtained results show that slow dynamic grain growth during superplastic flow is the key precondition for achieving superior superplastic properties in fine grained γ + α 2 alloys.

Effect of hot forging at lower temperatures, in the ordered α 2 + γ + β o / α 2 + γ phase field, followed by heat treatment on the microstructure and tensile properties has been studied for three β-solidifying γ-TiAl alloys. The alloy compositions were Ti-45Al-5Nb-1Mo-0.2B, Ti-43.7Al-4.2Nb-0.5Mo-0.2C-0.2B and Ti-44Al-5Nb-0.2B (at.%). The phase transformation sequences were defined for the alloys. Hot forging procedures for the Ti-45Al and Ti-43.7Al based alloys included forging in the temperature range of the α + γ + β(β o ) / α + α 2 + γ + β(β o ) and α 2 + γ + β o phase fields. This led to refined microstructures due to occurrence of dynamic recrystallization and globularization processes. The as-forged alloys showed excellent superplastic properties. Particularly, superior superplastic properties (El >>1000 % and low flow stresses), never reached in γ-TiAl alloys, were obtained for the Ti-43.7Al based alloy in the temperature range of 900 -1000°C. The Ti-44Al based alloy was subjected to upset forging using a small strain value in the temperature range of the α 2 + γ phase field. All forged alloys were further subjected to two-stage annealing in the α + γ + β(β o ) and α 2 + γ + β o or α 2 + γ phase fields. As a result, refined duplex microstructures were obtained in the alloys. Tensile tests were performed for the forged and heat treated alloys. They showed quite reasonable tensile properties as compared with those obtained in similar alloys after high-temperature hot forging followed by heat treatment. Particularly, the Ti-45Al-5Nb-0.2B alloy in the duplex condition exhibited El = 3.1 % and UTS = 860 MPa at room temperature and El = 6.5 % and UTS = 790 MPa at 700°C.

In the present work, the effect of alloying with dysprosium on microstructure and compression mechanical properties of a β-solidifying γ-TiAl alloy has been studied. For this, ingots of the alloys Ti-45Al-6(Nb,Mo)-0,2B-xDy (at.%) with various additions of dysprosium (x = 0, 0,1 and 1 at.%) were melted. The as-cast alloys were homogenized and then cooled in a furnace. These conditions of the alloys were assumed as the initial cast conditions. Microstructure examination showed that Ti-45Al-6(Nb,Mo)-0,2B and Ti-45Al-6(Nb,Mo)-0,2B-0,1Dy alloys had near lamellar microstructures in the initial conditions. Alloying with 1 at.% of dysprosium caused a change in the microstructure morphology from near lamellar to mixed lamellarglobular one. The appearance of globular γ and α 2 grains in the alloy alloyed with 1 at.% of dysprosium resulted in an appreciable refinement of the γ / α 2 colonies. It was revealed that the addition of 1 at.% of dysprosium to the Ti-45Al-6(Nb,Mo)-0,2B alloy led to changing the phase composition: along with the basic γ, α 2 and β(B2)-phases an additional DyAl 2 phase was detected. Also, oxide particles Dy 2 O 3 were revealed in both alloys containing dysprosium. The alloys under study were subjected to heat treatment, which included a three-stage anneal. As a result, near lamellar structure was obtained in all alloys. It has been established that the alloys containing dysprosium in the heat treated conditions demonstrated higher values of both the strength and ductility as compared to the alloy free of dysprosium. At T = 800°C, the compression mechanical properties of the alloys were found to be similar. В работе изучали влияние легирования диспрозием на микроструктуру и механические свойства на сжатие интерме-таллидного β-затвердевающего γ-TiAl сплава. Для этого были выплавлены слитки сплавов Ti-45Al-6(Nb,Mo)-0,2B-xDy (ат.%) с различным содержанием диспрозия (x = 0, 0,1 и 1 ат.%). Слитки сплавов подвергали гомогенизационному отжигу с последующим охлаждением в печи. Данное состояние было принято за исходное литое состояние. Выпол-ненные исследования показали, что микроструктура сплавов Ti-45Al-6(Nb,Mo)-0,2B и Ti-45Al-6(Nb,Mo)-0,2B-0,1Dy в исходном состоянии преимущественно пластинчатая. Введение в сплав 1 ат.% диспрозия приводит к изменению морфологии микроструктуры от преимущественно пластинчатой к пластинчато-глобулярной. Появление глобуляр-ных γ и α 2 -зерен в сплаве с 1 ат.% диспрозия сопровождается заметным уменьшением размера γ / α 2 колоний. Было показано, что введение 1 ат.% диспрозия в сплав Ti-45Al-6(Nb,Mo)-0,2B приводит к изменению фазового состава материала: кроме основных γ, α 2 и β(В2)-фаз в сплаве была обнаружена фаза DyAl 2 . Кроме того, в микроструктуре сплавов, содержащих диспрозий, также были обнаружены оксидные частицы Dy 2 O 3 . Для всех исследованных спла-вов была выполнена термическая обработка, включавшая в себя трехстадийный отжиг. В результате во всех сплавах была получена преимущественно пластинчатая микроструктура. Установлено, что сплавы, легированные диспрози-ем, в те...

The main proof of fusion reactions of deuterium nuclei is the presence of nuclear reaction products. When detecting tritium after saturation of titanium powders with deuterium reproducible results of its high concentration have been found. Titanium powders of two different batches have been used. According to metallographic studies, powder # 1 had an average particle size of d = 110 ± 5 μm; lazer diffraction analyzer of particle sizes registered one more maximum near the size of d = 0.2 μm. Powder # 2 was a sifted fraction with sizes in interval 80 < d < 150 μm. For powder # 1 the measured concentrations of tritum amounted about c T = (11 -14) • 10 3 dpm and for powder # 2 c T = (1.45 -1.57) • 10 3 dpm, a concentration typical for deuterium used. An effect of the dispersity of initial titanium powder on the proceeding of nuclear reactions has been demonstrated. Earlier, a mechanism of interaction of deuterons in a metallic matrix by means of a resonance transfer of a neutron from one deuteron to the other has been proposed. One of the products of such an interaction is a tritium nucleus. Such a process can run in elongated defects. The cross dimension of such defects was not known, however. From an analysis of measurements of titanium powder particle sizes one can conclude that the optimum size of pores must be about d 1 = 3 • 10 -8 m. During all experiments the levels of neutrons (N n = 30 ± 2 1 / 50 sec) and gamma quanta (N γ = 700 ± 15 1 / 5 sec) did not exceed the values typical for the room where experiments were carried out.Keywords: deuterium, tritum, cold fusion. Основным доказательством реакций слияния ядер дейтерия является наличие продуктов ядерных реакций. При из-мерении трития после насыщения дейтерием титанового порошка были зарегистрированы воспроизводимые ре-зультаты его высокой концентрации. Были использованы порошки титана двух разных партий. Порошок № 1 -средний размер частиц составлял d = 110 ± 5 мкм по металлографическим измерениям, кроме того на лазерном дифракционном анализаторе размеров частиц зарегистрирован еще один максимум с размером d = 0,2 мкм, и по-рошок № 2 -просеянная фракция (80 < d < 150 мкм). Для порошка № 1 измеренные значения концентрации трития составляли c T = (11 -14) • 10 3 dpm, а для порошка № 2 c T = (1,45 -1,57) • 10 3 dpm, концентрация, обычная для использо-ванного дейтерия. Показано влияние дисперсности исходного титанового порошка на протекание ядерной реакции. Ранее был предложен механизм взаимодействия дейтронов в металлической матрице за счет ре-зонансного переноса нейтрона от одного дейтрона к другому. Одним из продуктов такого взаи-модействия будет ядро трития. Такой процесс может протекать в длинномерных дефектах. Оста-ется вопрос о поперечном размере таких дефектов. Из анализа результатов измерения размеров частиц порошка титана можно сделать вывод, что оптимальный размер пор должен составлять d 1 = 3 • 10 -8 м. Во время всех экспериментов уровни нейтронов (N пn = 30 ± 2 1 / 50 сек) и гамма квантов (N пγ = 700 ± 15 1 / 5 сек) не пре-высили обычные величины д...

In silicate systems, which are very important in refractory technology, an equilibrium state is virtually unobtainable even with prolonged heat treatment. Therefore, in order to get close to the equilibrium state, it is necessary to carry out special preparation of the raw material by homogenizing it simultaneously with the fine milling of the components and by chemical codeposition followed by high-temperature firing or melting during which the synthesis of mullite is achieved.

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