Viscosity and electrical resistivity of liquid cunial, cunialco, cunialcofe alloys of equiatomic compositions

The kinematic viscosity and electrical resistivity of equiatomic liquid alloys CuNiAl, CuNiAlCo, CuNiAlCoFe has measured during heating of the sample to 2070 K and subsequent cooling. We consider CuNiAl, CuNiAlCo, CuNiAlCoFe alloys of equiatomic compositions as the multi-principal element alloys (MPEAs), the complex concentrated alloys (CCAs), the high-entropy alloys (HEAs). The measuring results of the vickosity and the resistivity are discussed on base the available microgeterogenity concept. We searched the temperatureT*of the heating a melt for destroy of microheterogeneity. T* is the temperature of the beginning of the matching portion of the temperature dependence of the viscosity and resistivity which is obtained by heating and cooling. All the investigated melts demonstrated different temperature dependence of viscosity for heating and cooling. The temperature T*=1800 K were determined only for liquid alloy CuNiAl of equiatomic composition. For alloys CuNiAlCo, CuNiAlCoFe the coinciding part of the temperature dependences of the viscosity which are obtained by heating and cooling is absent. The results of viscosity are discussed within the theory of absolute reaction rates. Entropy of activation of viscous flow and free activation energy of viscous flow were determined by analyzing the temperature dependences of kinematic viscosity. The increasing of components quantity in the alloy leads to the increasing of the free activation energy of viscous flow and the volume per structural unit of the melt (ion, atom, or cluster). The measuring results of resistivity were interpreted using the Nagel-Tauc model. The temperature coefficient of resistivity (characteristic of the structural state of the melt) was determined. The temperature dependences of the CuNiAl liquid alloy resistivity measured upon heating to 2070 K and subsequent cooling do not coincide.The value of T*temperature for alloy CuNiAl of equiatomic composition is 1850 K. For CuNiAlCo, CuNiAlCoFe alloys the temperature dependences of the resistivity which are obtained by heating and cooling are coinciding. This means that destroy of microheterogeneity for melts after heating up to 2070K did not occur. The temperature coefficient of resistivity of the CuNiA liquid alloy irreversibly decreases when it heated to a temperature of 1850 K.This is evidence of the destruction of microheterogeneity with the formation of a homogeneous solution at the atomic level. The increasing of components quantityin the alloy leads to a decreasingof thetemperature coefficient of the resistivity (in cooling moda). According to the ideas of Nagel and Tauk, an irreversible decrease of the temperature coefficient of the specific resistance of the melt indicates an increase in the volume per structural unit of the melt (ion, atom, or cluster). © 2019, Technical University of Kosice. All rights reserved.Authors are grateful for the support of experimental works by Act 211 Government Russian Federation, contract 02.A03.21.0006

Viscosity and separation of Fe-Cu melts

A viscosimetric study of Fe-Cu melts is performed on heating and subsequent cooling of samples. The results of measurements in the above-liquidus part of the phase diagram are used to construct the boundaries of colloid-scale microheterogeneities in a melt. © 2013 Pleiades Publishing, Ltd

Influence of copper additives on the viscosity and stratification of iron melt

Viscosimetric data are obtained for Fe-Cu melts in heating and subsequent cooling of samples with 0-10 wt % Cu. Above the liquidus in the resulting phase diagram, the boundaries of the region where microheterogeneities of colloidal scale exist in the melt are found. © 2013 Allerton Press, Inc

Method for obtaining ingots of the A34 solder based on an investigation into the relation between the structure and properties of liquid and solid metals

A comparative analysis of the influence of the modifying method on the structure and phase composition of the ingots of the A34 solder is performed. Modification is performed by force of heating the melt to 1000°C and introducing the fine-crystalline remelt in an amount of 5% of the charge amount into the melt. The investigation is performed using DTA and metallographic analysis. The structure of the ingot of the A34 solder is additionally investigated at elevated temperatures (150 and 300°C) by the sc-AFM method using the NTEGRA Therma probe nanolaboratory, and recommendations are given to optimize the modes of casting and thermal treatment. © 2013 Allerton Press, Inc

Influence of defects on the ductility of liquid 9X2MΦ and 75X3MΦ steel

Viscosimetric data on liquid 9X2MΦ and 75X3MΦ steel taken from working rollers of a reversible rolling mill with different ultrasonic behavior illustrate the influence of defects recorded in ultrasound monitoring on the temperature and time dependence of the liquid steel's kinematic viscosity. A Krautkremer ultrasonic defectoscope is employed in monitoring. The viscosity of the liquid steel is measured by means of damping torsional oscillations of a crucible with melt in heating and subsequent cooling in the range 1500-1580°C. © 2013 Allerton Press, Inc

Examining the structure of mill rolls made of 9X2MΦ and 8X3CΓΦ steels using the ultrasonic method for quality control

The microstructure of specimens of 9X2MΦ and 8X3CΓΦ steels taken from working rolls of a reversing mill was examined. A correlation between characteristics of the crystal structure of the metal and the intensified attenuation of ultrasonic waves was found. Ultrasonic inspection was carried out using an ultrasonic flaw detector (Krautkramer Co.). The microstructure was examined by means of traditional metallographic analysis methods, which were implemented using a scanning electron microscope; X-ray spectral microanalysis and electron backscatter diffraction were used. The morphology and elemental composition of discontinuity flaws were studied; as well, phase maps, crystallite misorientation histograms, and Taylor factor maps were plotted for specimens taken from the defect zone of a 9X2MΦ steel working roll. © 2013 Pleiades Publishing, Ltd

Measurement of young's modulus and hardness of Al-50 wt % Sn alloy phases using nanoindentation

The nanoindentation method was used to measure the Young's modulus and hardness of the phases of the alloy Al-50 wt % Sn: α-aluminum and eutectic. Samples are obtained in different ways, i.e., traditionally via the transition of the melt into a homogeneous structural state by heating to a certain temperature, followed by cooling using the cooling rate greater by the order than that of the traditional method and via the addition of 0.06 wt % Ti and 1 wt % Zr to the binary alloy. It has been found that the most significant effect of the Al-50 wt % Sn phases on the Young's modulus is the transition of the melt into a homogeneous structural state and the introduction of Zr into the melt. As part of the mathematical theory of elasticity, a numerical evaluation of the interfacial pressure that arises due to the difference between Young's modulus of α aluminum and eutectic has been performed. The calculation has showed that the extra pressure is nine times less for the alloy formed through the transition of the melt into a homogeneous structural state than for the alloy produced via a traditional way. © 2013 Pleiades Publishing, Ltd

Surface Tension and Density of Fe–Mn Melts

Abstract: The article presents original experimental data on surface tension of the Fe100 – xMnx (x = 4–13 wt %) melts. Surface tension and density of the melt were measured by the sessile drop method at heating from the liquidus temperature to 1780°C and subsequent sample cooling in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe–Mn melts were plotted. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe–Mn melts decreases as Mn content increases. Experimental data on the surface tension of Fe–Mn melts is consistent with the theoretical dependences (the Pavlov–Popel’ equation and the Shishkovsky equation). During the investigation of Fe–Mn melt microheterogenity, correlation between the values of kinematic viscosity, surface tension, and density is revealed. Fluidity dependence of Fe–Mn melts on their density in the cooling mode has a linear character which indicates satisfaction of the Bachinskii law. Discrepancy in the melt viscosity ratios to the surface tension coefficient obtained from the experimental data and from the empirical formula is discovered. Using the experimental data on viscosity and surface tension of Fe–Mn melts, the entropy change in the melt’s bulk and the change in the melt’s surface entropy, respectively, are studied. The surface entropy and the bulk entropy in the melt decrease in their absolute value with its increasing Mn content. From the study results, it is concluded that there is no destruction of the microheterogeneous structure of Fe100 – xMnx (x = 4–13 wt %) melts when heated up to 1780°C. © 2020, Allerton Press, Inc.The reported study was funded by Russian Foundation for Basic Research, project no. 19-33-90198

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СТРУКТУРНОГО СОСТОЯНИЯ РАСПЛАВА НА КРИСТАЛЛИЧЕСКОЕ СТРОЕНИЕ И МЕХАНИЧЕСКИЕ СВОЙСТВА ФАЗ СПЛАВА AL-50 МАС.%SN МЕТОДОМ НАНОИНДЕНТИРОВАНИЯ

Nanoindentation is used to measure Young's modulus, the hardness, the plasticity, and the yield strength of the phases in Al-50 wt % Sn alloy samples prepared by a traditional method and using liquid-state homogenization. The effect of an increase in the cooling rate by an order of magnitude and alloying with 0.06 wt % Ti or 1 wt % Zr on the mechanical properties of the phases in the Al-50 wt % Sn alloy is studied. The most substantial effect on Young's modulus of the phases in the Al-50 wt % Sn alloy is found to be exerted by the homogenization of the metallic liquid and the introduction of zirconium in the alloy melt: the metal forming of an ingot is improved substantially. © 2013 Pleiades Publishing, Ltd

Structure of diffusion layers formed at liquid aluminum alloy-steel contact boundary

The microstructure and composition of diffusion layers that arise upon the spread of the liquid aluminum alloys AL5, AL9, AL852, and A7075 over the St3 steel has been investigated using optical and electron microscopy. The thermophysical conditions of the interaction of the melt with the substrate under which at the boundary of the substrate the plastic transition layer of iron-based solid solution improving quality of the coating is formed have been determined. © 2013 Pleiades Publishing, Ltd