Currently, biosoluble materials are widely used for the manufacture of implants, among which the most promising are magnesium alloys. Magnesium is a natural element of the body -it is contained in bone and muscle tissue, is involved in various metabolic processes. In addition, magnesium and its biocorrosion products have excellent biocompatibility. The main advantage of magnesium alloys is the positive effect of magnesium on the human body, but their quality does not meet the requirements for their use in the human body. It is possible to increase the properties of magnesium alloys as a result of improving the processes of refining and modification of liquid melt. The technology of modification of cast magnesium alloys of Mg-Zr-Nd system by dispersed graphite powder is proposed. It is shown that the optimal carbon additive in the amount of 0.05 -0.1 wt% C improves the mechanical properties due to grain grinding and additional strengthening of structural components. A complex filter containing equal amounts of magnesite, graphite and limestone is proposed, which provides an increased level of refining of the melt to obtain high quality casting. It is shown that the use of a complex carbon-containing filter provides not only efficient refining of the melt, but also its additional modification. In the structure of the alloy there is an increased amount of intermetallic γ-phase, which increases the microhardness of the structural components of the alloy and improves its physical and mechanical characteristics.
Визначено кінетичні закономірності вуглецевотермічного відновлення оксидного молібденового концентрату в інтервалі 873-1473 K. Найвищий ступінь відновлення 97 % досягнуто після обробки при 1373 K із переважанням у фазовому складі Mo. Мікроструктурагубчаста розупорядкована. Поліпшення екологічної безпеки досягається заміною вуглецевосиліко-та алюмотермічної плавок феросплавного виробництва Mo на новітні методи порошкової металургії Ключові слова: молібденовий концентрат, вуглецевотермічне відновлення, металізація, сублімація, фазовий аналіз, мікроструктура, ресурсозбереження Определены кинетические закономерности углеродотермического восстановления оксидного молибденового концентрата в интервале 873-1473 K. Наибольшая степень восстановления 97 % достигнута после обработки при 1373 K с преобладанием в фазовом составе Mo. Микроструктура-губчатая разупорядоченная. Улучшение экологической безопасности достигается заменой углеродосилико-и алюмотермической плавок ферросплавного производства Mo на новейшие методы порошковой металлургии Ключевые слова: молибденовый концентрат, углеродотермическое восстановление, металлизация, сублимация, фазовый анализ, микроструктура, ресурсосбережения
The temperature and degree of hot deformation for steel 10HFTBch have been determined. This made it possible to ensure an increase in the mechanical properties of this steel, namely, the ultimate strength up to 540–560 MPa, as well as the relative elongation up to 25–29 %. As a result, it became possible to increase the service life of wheels with increased carrying capacity. This, in turn, will make it possible to increase the load of the transported cargo by motor vehicles several times. The mechanism of the influence of the energy-power parameters of rolling on the formation of the macro- and microstructure of a two-phase steel in the process of hot deformation is disclosed. The applied scheme provided an increase in the homogeneity of the structure of the developed steel, which saved the central part of the rolled section from overheating. It has been established that a decrease in the temperature of the end of deformation leads to a decrease in the size of the recrystallized austenite grain, and, consequently, to a refinement of the ferrite grain. Also an important factor in preventing the growth of ferrite grains in the upper part of the ferritic region is the abolition of cooling of the steel in coils. The recommended mode for multicomponent alloy steel 10HFTBch is as follows: the temperature of the end of rolling is 850 °C, the beginning of accelerated cooling is 750 °C, and the temperature of strip coiling into a coil is 600 °C. The basis for ensuring the increased strength of two-phase steels is the ratio and distribution of structural fractions – ferrite (initial and precipitated from austenite), as well as martensite. When hardened by such traditional "martensite formations" as manganese, the ability to control properties is limited. This is reflected in a narrow range of variation in the strength and ductility of the developed steel. The optimal combination of strength characteristics of plastic properties reduces the metal consumption of the product by 15–25 %.
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