Laves Phase Formation in High Entropy Alloys

One of the intriguing recent results in the field of high-entropy alloys is the discovery of single-phase equiatomic multi-component Laves intermetallics. However, there is no clear understanding that a combination of chemical elements will form such high-entropy compounds. Here we contribute to understanding this issue by modifying the composition of duodenary TiZrHfN-bVCrMoMnFeCoNiAl (12x) alloy in which we recently reported the fabrication of hexagonal C14 Laves phase. We consider three alloys based on 12x: 7x = 12x-VCrMoMnFe, 12x + Sc, 12x + Be and observe that all of them crystalize with the formation of C14 Laves phase as a dominant structure. We report that 12x + Be alloy reveals a single-phase C14 structure with a very high concentration of structural defects and ultra-fine dendritic microstructure with an almost homogenous distribution of the constituted elements over the alloy matrix. The analysis of electrical and magnetic properties reveals that the Laves phases are Curie-Weiss paramagnets, which demonstrate metallic conduction; 7x and 12x alloys also reveal a pronounced Kondo-like anomaly. Analysis of experimental data as well as ab initio calculations suggest that chemical complexity and compositional disorder cause strong s-d band scattering and thus the rather high density of d-states in the conduction band. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgments: Experiments were performed using scientific instruments included in the Collective Equipment Center “Ural-M” and the “Geoanalitik” shared research facilities of the IGG UB RAS. The re-equipment and comprehensive development of the "Geoanalitik" shared research facilities of the IGG UB RAS is financially supported by the grant of the Ministry of Science and Higher Education of the Russian Federation (Agreement No. 075-15-2021-680). The numerical calculations are carried out using computing resources of the federal collective usage center ‘Complex for Simulation and Data Processing for Mega-science Facilities’ at NRC ‘Kurchatov Institute’ (accessed on ckp.nrcki.ru/, 11 January 2021) and Joint Supercomputer Center of Russian Academy of Sciences (accessed on www.jscc.ru, 1 January 2021)

EFFECT OF TITANIUM ON THERMOPHYSICAL PROPERTIES OF GLASS-FORMING ALLOYS Cu-Zr

High-temperature studies of thermal diffusivity and structural transformations in Cu50Zr50 and Cu50-xZr50-xTix alloys (x = 0 - 8 at.%) under controlled heating conditions were carried out. The sequence and type of reactions were determined under the thermal treatment of Cu-Zr-Ti alloys over a wide temperature range.Работа выполнена при финансовой поддержке РФФИ (№ гранта 16-02-00835)

The Digitalization of Russian Politics and Political Participation

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Metastable microheterogeneity of melts in the Ga-Bi system with limited solubility of components in liquid state

A set of acoustic (using the pulse phase method for ultrasound velocity v (s) measurement) and gamma-absorption experiments with the Ga-Bi melts have been performed to clear the nature of their microinhomogeneity. Both methods allow determining upsilon (s) and intensity of the penetrating gamma-beam, I, at various distances, h, from the bottom of the measuring cell. Distinct upsilon (s)(h) and I(h) dependences were discovered in one phase domain of the phase diagrams. It is clear that such inhomogeneity is connected with the chemical inhomogeneity of the melt which, in its turn, can exist if one of the components forms very large particles containing 10(4)-10(5) atoms. The cupola-like borders of the domains where such inhomogeneity exists were fitted in the phase diagrams of the systems under investigation. The inhomogeneity has been confirmed in special acoustic experiments with superposition of ultrasound and low-frequency oscillation

Density studies of liquid alloys Sn-Ag and Sn-Zn with near eutectic compositions

The authors gratefully acknowledge the financial support of the Russian Foundation for Basic Research under the contract 10-03-96043. This work was also supported by the projects VEGA 2/0111/11, APVV-0413-06, APVV-0647/10 and by the Centre of Excellence SAS FUN-MAT. This research contributes to the European COST Action MP0602 on Advanced Solder Materials for High Temperature Applications.The density values for Sn - Ag and Sn - Zn alloys with near eutectic compositions were determined by the gamma-absorption method both in the liquid and solid states. Sn-rich melts of the Ag-Sn system were found to be microheterogeneous, whereas Sn-Zn melts demonstrate the behavior typical for true solutions. (C) 2012 Elsevier B.V. All rights reserved

Density studies of liquid alloys Sn-Ag and Sn-Zn with near eutectic compositions

The authors gratefully acknowledge the financial support of the Russian Foundation for Basic Research under the contract 10-03-96043. This work was also supported by the projects VEGA 2/0111/11, APVV-0413-06, APVV-0647/10 and by the Centre of Excellence SAS FUN-MAT. This research contributes to the European COST Action MP0602 on Advanced Solder Materials for High Temperature Applications.The density values for Sn - Ag and Sn - Zn alloys with near eutectic compositions were determined by the gamma-absorption method both in the liquid and solid states. Sn-rich melts of the Ag-Sn system were found to be microheterogeneous, whereas Sn-Zn melts demonstrate the behavior typical for true solutions. (C) 2012 Elsevier B.V. All rights reserved

The Kinematic Viscosity of Liquid Copper-Aluminum Alloys

The method of damped torsional vibrations of crucible with liquid under investigation is used for measuring the temperature dependences of kinematic viscosity v of Cu(100-x)Al(x) melts (x = 0-100 at.%) in the range of temperatures t between the liquidus and 1100-1450 degrees C. Unlike the majority of such experiments, the measurements are performed both in the process of heating the sample after its melting and in the course of subsequent cooling. The branching of v(t) curves corresponding to the foregoing modes is revealed below certain temperatures dependent on the composition of sample (viscosity hysteresis). The curves obtained under cooling have a simple exponential shape predicted by activation theories of viscous flow. The obtained temperature dependences are used for constructing isotherms of kinematic viscosity, on which maxima are observed in the vicinity of stoichiometric concentration of CuAl(3) and composition of Cu-30 at.% Al. For the same compositions, extrema are observed on the concentration dependence of activation energy of viscous flow