Papers by Keyword: Liquid Metal

Abstract: Free surface motion of a liquid metal submerged in an alternating magnetic field has been examined. A copper vessel filled with a liquid gallium is set in a coil for the imposition of the alternating magnetic field. The alternating magnetic field penetrates into a liquid gallium only from an upper free surface because thickness of the copper vessel is larger than the electromagnetic skin layer of copper. Time variation of displacement of the standing wave loop excited on the free surface is detected by a laser level sensor. The standing wave was suppressed not only by intensification of the magnetic field magnitude but also increase of the magnetic field frequency.

Abstract: A molecular dynamics simulation study has been performed for a large-sized system consisting of 106 liquid metal Al atoms to investigate the evolution characteristics of nano-clusters formed during rapid solidification processes. The cluster-type index method (CTIM) has been applied to describe the structural configurations of the basic clusters and nano-clusters. The results show that the icosahedral clusters (12 0 12 0) and their combinations play a critical role in the microstructural transitions. The nano-clusters are mainly formed by combining basic and medium sized clusters through continuous evolution. Their structural configurations are different from the multi-shell structures obtained by gaseous deposition, ionic spray, and so on. The central atoms of basic clusters composing the nano-cluster are bonded with each other, some central atoms are multi-bonded, and others single-bonded.

Abstract: A molecular dynamic simulation study has been performed for a large-sized system consisting of 106 liquid metal Al atoms to deeply investigate the formation and magic number characteristics of various cluster formed during solidification processes. It has been found that the numbers of various types of cluster in the system obviously possess peak values, namely, magic numbers. The first, second, third, .…,and tenth magic numbers are determined in turn in the order of 13, 19, 25(27), 31(33), 38(40), 42(45), 48(51), 55(59), 61(65), 67,…( the numbers in the brackets are the second peak values in the corresponding level of cluster). This magic number serial is in good agreement with the experimental results obtained by Harris et al, and this method determining the magic numbers from the clusters according to the level of basic cluster can be used to afford a primary scientific and reasonable explanation to experimental results.

Abstract: In the present paper the wettability of a liquid metal by another liquid metal is studied theoretically, based on a recent model on interfacial energies in metallic systems. It appears that in all practical cases the liquid metal with a lower surface tension will perfectly wet (with a zero contact angle) the liquid metal with a higher surface tension practically at any temperature, and therefore will encapsulate it. As a result, the first order surface phase transition will start in monotectic metallic systems at 0 K. The phenomenon of the surface phase transition is considered in some details, based on a recent paper.

Abstract: Six different theoretical equations are compared in the present paper with experimental data, measured for 28 binary liquid metallic systems. General conclusions are drawn on the ability of the different theoretical models to describe the concentration and temperature dependence of the viscosity of liquid alloys. A new equation is derived, being able to predict the viscosity in multicomponents alloy even if the viscosities of the pure components are not known.

Abstract: Industrial alloys are generally multi-component systems with volatile and highly reactive components. Consequently, their processing in the liquid state requires special precautions. Therefore, an existing electromagnetic-levitation device with a high-vacuum chamber, designed for surface tension measurements, was modified and improved. For the measurements of the surface tensions with the help of the oscillating drop technique the temperatures and the video sequences of the levitated, molten alloy were recorded without contact by pyrometer and by high-speed camera, respectively. This method yields the frequencies of the surface oscillations of the sample around the equilibrium shape and - using the modified Rayleigh law - eventually the values of the surface tension. With the help of this method two commercial industrial steels were processed in the new EML-apparatus for ESA`s Thermolab project [1]. The results of these measurements are presented and discussed

Abstract: Liquid Cu-Co shows a metastable miscibility gap where the homogeneous melt separates into the Co-rich L1-liquid and the Cu-rich L2-liquid. The required undercooling of the melt of > 120 K can be achieved by containerless methods as electromagnetic levitation, laser melting or drop tube processing. Due to the large undercooling, rapid solidification of the melt is favoured and preserves microstructure features of the metastable (liquid) phases. In Co-84.0 at% Cu alloy the L1- phase nucleates in the Cu-rich majority phase L2 as a dispersion of spherical droplets. Convective flow in the liquid influences largely the time evolution and the nature of the droplet dispersion and makes a theoretical description of the droplet growth extremely difficult. In the present work droplet dispersions are compared which formed under processing methods with different levels of convection: (i) (Terrestrial) electromagnetic levitation (EML), (ii) processing in the TEMPUS facility under parabolic flight conditions and (iii) processing in an 8 m drop tube. The distributions of droplet radii of the L1-phase has been measured in the solidified samples. EML processing leads to significant convection in the melt which causes coagulation of droplets. Reduced gravity conditions in the TEMPUS facility during parabolic flight or in a drop tube can decrease convection, but effects of the convective flow on the dispersion of droplets are still present. The need for experiments under micro-gravity conditions is evident from the results.

Abstract: After some biographical notes, Fick’s 1855 seminal paper is analysed and the contributions of Stefan and Roberts-Austen are briefly mentioned.

Abstract: The aim of this paper is to review all the existing literature models on the concentration dependence of the viscosity of binary liquid alloys and to check them against the measured viscosity values in the binary liquid Cu-Ag system at 1373K.