A computer-aided plant for studying the kinematic viscosity of high-temperature metallic melts

Konashkov, V. V.; Цепелев, В. С.; V’yukhin, V. V.; Povodator, Arkadi; Podol’skaya, A. I.

doi:10.1134/s0020441211020187

Cited by 18 publications

(16 citation statements)

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“…1a, the viscosity and the activation energy of liquid aluminum decrease with admixtures of silicon. The viscosity curves of liquid Al-Si alloys are in close agreement with earlier reported data for Al-Si alloys measured by the same oscillating-cup method [16]. The Al-Si system phase diagram is of a simple eutectic type [19].…”

Section: Resultssupporting

confidence: 80%

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VISCOSITY END ELECTRICAL CONDUCTIVITY OF LIQUID HYPEREUTECTIC ALLOYS Al-Si

Чикова

Никитин

Moskovskikh

2016

Acta Metall Slovaca

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The kinematic viscosity of AlSi20 liquid alloy was measured by using the crucible rotating oscillation damping method, and the viscosity-temperature relation curve ν(T) in the temperature range of 850∼1200K was obtained. The viscosity changed abnormally with temperature in the heating process, i.e., the viscosity turned from rapid increase to gradual decrease when the temperature increased to 1000∼1100 K, while the viscosity diminishes exponentially with temperature in the subsequent cooling process. The microscopic mechanism of the evolution of viscosity was analyzed from the viewpoint of the micro-inhomogeneity theory of metallic melts, and it was found that the destruction of the β-Si phase was the basic reason of the head-turning change of viscosity. The paper discussed the correlation of the viscosity and atomic density, which is thought that the viscosity corresponds to the atomic density to some extent. The abstract should be written in the past tense, because it refers to work which was already done. Any equations and references are not allowed. It must state the main object, scope, findings, describe the methodology, summarize the results and state the principal conclusions.Keywords: aluminium alloys, liquids, crystallization, microstructure, segregation 1 Introduction Al-Si alloys are amongst the most widely used industrial metallic alloys due to a combination of good cast ability and mechanical performance [1]. Modification of the complex solidification microstructure, aimed at improving the process ability and the mechanical performance, has received continued research attention in these alloys [2][3][4]. Were investigated of influence of melt overheating (up to defined temperature for each alloy) on structure and phase composition of ingots hypereutectic silumi [5]. It is shown that hypereutectic silumin melt keeps the inhomogeneous state in a wide range of overheating above the liquidus temperature ТL, and the most significant structure rearrangement is observed only when heated above the temperature Тk. The large amount of eutectic and primary coarse Si-flakes that form during solidification of the Al-Si hyper-eutectic alloys leading to reduced ductility and wear performance [6][7]. The sessile-drop method and high-temperature small-angle x-ray diffraction technique were used in work [8] to characterize the density of liquid Al-Si alloys with Si content to 22 wt.%. A distinct abnormal volume expansion of the hyper-eutectic melts was identified just above the liquidus (within TL-Tk) during the heating sequence, which is irreversible during the cooling sequence. This phenomenon is explained by the segregation of Si atoms from the supersaturated "quasi-

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Section: Resultssupporting

confidence: 80%

“…During the measurements, the oscillation parameters were detected by an optical method using a system of oscillation photo detection. The techniques of measure and processing experimental data were described in detail in [16]. The copper and tin Reagent grade served as charge materials.…”

Section: Experimental Materials and Methodsmentioning

confidence: 99%

VISCOSITY END ELECTRICAL CONDUCTIVITY OF LIQUID HYPEREUTECTIC ALLOYS Al-Si

Чикова

Никитин

Moskovskikh

2016

Acta Metall Slovaca

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“…Measurement error for values of kinematic viscosity did not exceed 3%. The measurement of kinematic viscosity was performed on the device described in [20][21].…”

Section: Methodsmentioning

confidence: 99%

ON THE INFLUENCE OF SCANDIUM ON THE FLUIDITY OF THE AlMg6Li2 MELTS

Чикова

Ovsyannikov²,

Резник

2016

Acta Metall Slovaca

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We conducted the study of viscosity liquid alloys AlMg6Li2(Sc) under the heating and subsequent cooling of samples. Results of these measurements allowed defining critical temperatures. The processing melt by heating above the critical temperature cause irreversible destruction of microinhomogeneities of hereditary nature. The irreversible destruction of micro-inhomogeneities improves the casting properties of the melts AlMg6Li2(Sc).Keywords: alloys Al-Mg-Li-Sc, microstructure, EDS-analysis, melt, viscosity, fluidity, temperature-time processing of melt IntroductionThe alloys based on Al-Mg-Li system are being actively developed over the last years. Aluminum alloys containing lithium have a number of advantages in comparison with aluminum alloys based on other systems: their specific mass is averagely 10% lesser and the modulus of elasticity is 12% higher. Moreover, aluminum-lithium alloys can possess high mechanical characteristics (tensile strength reaches 600-650 MPa) with the good factors of crack resistance and corrosion resistance [1][2][3]. Despite all these advantages, AlMg6Li2 alloys are not widely used, mainly because of the low technological plasticity [4]. Reduced plasticity of annealed alloys with lithium is associated with high alloying and high volume ratio of phases compared to traditional alloys and also, to a lesser extent, with the incompleteness of recrystallization, reason for this is the large number of interfering particles Al3(Zr,Sc,Li)β'-phase [4][5]. Magnesium content has a strong influence on technological plasticity of annealed alloys of system Al-Li-Cu-Mg-Zr [5]. The studies have shown that annealing process at 400-530°Cfollowed by slow cooling results only in formation of phaseT2 (Al6CuLi3) [5]. The measurements of the lattice period allowed determining that nearly all of magnesium in alloy remains in solid solution after annealing, a small portion of it is included in T2-phase and precipitates under annealing. Reducing of plasticity of annealed alloys mainly correlates with the high content of magnesium in solid solution and also with increasing of T2-phase quantity. Structural studies have demonstrated [2,5] that the main reason for low plasticity of annealed alloys of this system is a big volume fraction of δ'-phase (Al3Li) particles not crossed by dislocations or β'-phase composite particles with δ'-phase shells. These particles larger than

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Section: Introductionmentioning

confidence: 99%

“…The version based on measuring the logarithmic decrement (LD) of the torsional vibrations of a cylindrical cup with a melt suspended by an elastic filament is most widely applied in practice [2][3][4][5]. According to [1][2][3][4][5], the total calculated relative error of determining the absolute values of viscosity is 0.7-6% for analogous measurement techniques and means. Despite such a high declared measurement accuracy, the data of different authors on the viscosity of melts, especially pure liquid melts, are often conflicting in both absolute value and the character of temperature dependence (see, e.g., [5]).…”

Section: Introductionmentioning

confidence: 99%

Torsional vibration measurement of the viscosity of a metallic melt

2016

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The liquid Co 91 B 9 alloy is used as an example to study the influence of boundary conditions at the upper melt boundary on the results of viscosity measurements using torsional vibrations. Specific features related to film effects and wetting phenomena are shown to appear in the temperature dependence of logarithmic decrement. To exclude the influence of these effects and phenomena, viscosity measurements should be performed under the experimental conditions where the melt to be studied is in closed volume and the internal crucible walls are fully wetted. The temperature dependence of the kinematic viscosity of the Co 91 B 9 melt that is obtained under such experimental conditions has a monotonic character.

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A computer-aided plant for studying the kinematic viscosity of high-temperature metallic melts

Cited by 18 publications

References 0 publications

VISCOSITY END ELECTRICAL CONDUCTIVITY OF LIQUID HYPEREUTECTIC ALLOYS Al-Si

VISCOSITY END ELECTRICAL CONDUCTIVITY OF LIQUID HYPEREUTECTIC ALLOYS Al-Si

ON THE INFLUENCE OF SCANDIUM ON THE FLUIDITY OF THE AlMg6Li2 MELTS

Torsional vibration measurement of the viscosity of a metallic melt

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