Features of Amorphization of the Fe-TM-Nd-REM-B Alloys System at Melt Quenching by Gas Atomization

Gas atomization powders (GAP) chemical composition which corresponds to the first area of the phase equilibrium, and the fraction that ensures a cooling rate of a separate powder particle of more than 103K/s contains an amorphous component of two types: the first (AC1) has a chemical composition similar to that of the alloy; and the second (AC2) has a chemical composition of the triple eutectic. AC1 is mostly localized on the surface of the powder particles (in the form of layers, shells, nodules) or are detected in the whole volume of the spherical powder particles with its size less than 5 μm. The authors hold that during gas atomization, powder particles of this size have a cooling rate ≥ 105 K/s. Alloys having a similar chemical composition at similar cooling rates are also amorphized by quenching from the liquid state. This proves that an amorphous alloy of the first type is formed directly from a supercooled melt. While AC2 (enriched by Nd) is formed on the border or in the between the crystal phase Fe14Nd2B of the remaining (after primary crystallization during the primary phase) melt enriched by the moment of the solidification of Nd.

CO2 absorption and desorption characteristics of MgO-based absorbent promoted by triple eutectic alkali carbonate

We present the details of the mechanism of CO2 absorption and desorption of MgO absorbent promoted by triple eutectic alkali carbonate.

PHASE EQUILIBRIA IN SYSTEM (LiF)2 – (NaCl)2 – Na3FSO4

The liquidus surface of the quasi-triple system LiF–NaCl–Na3FSO4 was studied by a differential-thermal method of physicochemical analysis. As a result of the studies, the crystallization temperature (554 °C) and the composition of the three-component eutectic, which can be used as a heat accumulator in thermal energy storage devices, are determined. When designing plants based on renewable energy sources, it is necessary to provide storage tanks for the concentration of thermal energy, so that the stored heat energy can be used even in the period of absence of solar radiation. The most suitable for thermal accumulation are salt eutectic mixtures. Priority in this respect is research devoted to the development of compositions as possible with large values of the latent heat of the solid-liquid phase transition. The experiment was carried out on the synchronous thermal analysis unit STA 449 F3 Phoenix, the company Netzsch, designed to operate in the temperature range from room temperature to 1500 ° C in an atmosphere of inert gases (argon). All facet triangle (LiF)2 – (NaCl)2 – Na3FSO4: stable diagonal (LiF)2 – (NaCl)2 of the triple mutual system Li, Na // F, Cl and quasibinary systems: LiF–Na3FSO4; NaCl – Na3FSO4 is of the eutectic type, therefore it can be assumed that a triple eutectic is formed in the system. To determine the thermo physical characteristics of the eutectic composition, the experiment is planned in accordance with the general rules of the projection-thermographic method. The one-dimensional polythermal section AB located in the crystallization field of lithium fluoride, where A is 50% (LiF)2+ 50% Na3FSO4, B is 50% (LiF)2+ 50% (NaCl)2 was experientally studied. The study of the AB section reveals the direction to the triple eutectic, from the poles of lithium fluoride crystallization, i.e. the study of this section revealed a constant ratio of sodium chloride and sulfate-sodium fluoride in the triple eutectic. At the point showing a constant ratio of the two initial components in the eutectic, the thermal effects of the secondary and tertiary crystallizations are combined, and the primary crystallization is fixed at 657 °C. This composition is the starting point for the investigation of the next section. The content of lithium fluoride in the eutectic is determined by studying the polythermal section of lithium fluoride from the crystallization pole and passing through the projection Ē to the side of the triangle (NaCl)2 – Na3FSO4. As a result of the studies, the crystallization temperature and the concentration of the initial salts in the triple eutectic have been established. The detected eutectic composition (EΔ) crystallizes at 554 °C and contains eq. %: (LiF)2 – 26; (NaCl)2 – 23; Na3FSO4 – 51.Forcitation:Omarova S.M., Verdieva Z.N., Alkhasov A.B., Magomedbekov U.G., Arbukhanova P.A., Verdiev N.N. Phase equilibria in system (LiF)2 – (NaCl)2 – Na3FSO4. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 10. P. 4-8