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Showing papers on "Liquid metal published in 2004"


Journal ArticleDOI
TL;DR: In this paper, a closed loop system based on liquid metals and liquid metal pumps was proposed to achieve heat transfer coefficients on the order of 10W∕cm2∕K and miniature pumps operating at greater than 8kPa maximum pressure rise and 1% maximum efficiency.
Abstract: High electrically conducting fluids such as liquid metals offer a unique solution to the current and future cooling needs of high power density heat sources. The two principal advantages of developing single phase cooling systems based on liquid metals lie in their superior thermophysical properties and in the ability to pump these liquids efficiently with silent, nonmoving pumps. Closed loop systems based on liquid metals and liquid metal pumps enable gravity independent high performance cooling systems. Analytical and experimental work is presented showing heat transfer coefficients on the order of 10W∕cm2∕K and miniature pumps operating at greater than 8kPa maximum pressure rise and 1% maximum efficiency.

171 citations


Patent
30 Jan 2004
TL;DR: In this article, a heat spreader is divided into one or more chambers and electromagnetic pumps are placed inside each chamber in a configuration that facilitates easy circulation of liquid metal inside the chamber.
Abstract: Apparatus to provide effective removal of heat from a high power density device. The apparatus has a heat spreader and a heat sink structure. The heat spreader is divided into one or more chambers. Electromagnetic pumps are placed inside each chamber in a configuration that facilitates easy circulation of liquid metal inside the chamber. The liquid metal preferably is an alloy of gallium and indium that has high electrical conductivity and high thermal conductivity. The liquid metal carries heat from a localized area (over the high power density device) and distributes it over the entire spreader. This results in a uniform distribution of heat on the base of the heat sink structure and hence effective removal of heat by the heat sink structure.

116 citations


Journal ArticleDOI
TL;DR: In this article, a general view of discontinuous structural phase transition of liquid metal and alloys induced by the temperature is presented based on the viscosity analyses for more than ten kinds of liquid metals.

89 citations


Journal ArticleDOI
TL;DR: In this article, a continuous zone melting technique was developed to fabricate long rod and plate-shape porous metals and alloys even with low thermal conductivity, and the physical properties of these materials were described together with internal friction, elasticity, thermal conductivities and sound absorption characteristics.
Abstract: Lotus-type porous metals whose long cylindrical pores are aligned in one direction were fabricated by unidirectional solidification in a pressurized gas atmosphere. The pores are formed as a result of precipitation of supersaturated gas when liquid metal is solidified. The lotus-type porous metals with homogeneous size and porosity of the evolved pores produced by a mould casting technique are limited to the metals with high thermal conductivity. On the other hand, the pores with inhomogeneous pore size and porosity are evolved for metals and alloys with low thermal conductivity such as stainless steel. In order to obtain uniform pore size and porosity, a new “continuous zone melting technique” was developed to fabricate long rod- and plate-shape porous metals and alloys even with low thermal conductivity. Mechanical properties of tensile and compressive strength of lotus-type porous metals and alloys are described together with internal friction, elasticity, thermal conductivity and sound absorption characteristics. All the physical properties exhibit significant anisotropy. Lotus-type porous iron fabricated using a pressurized nitrogen gas instead of hydrogen exhibits superior strength.

87 citations


01 Feb 2004
TL;DR: In this article, the velocity of the liquid metal in the weld pool increased with time during heating and convection played an increasingly important role in the heat transfer, and the peak temperature and velocity increased significantly with laser power density and pulse duration.
Abstract: Alloying element loss from the weld pool during laser spot welding of stainless steel was investigated experimentally and theoretically. The experimental work involved determination of work-piece weight loss and metal vapor composition for various welding conditions. The transient temperature and velocity fields in the weld pool were numerically simulated. The vaporization rates of the alloying elements were modeled using the computed temperature profiles. The fusion zone geometry could be predicted from the transient heat transfer and fluid flow model for various welding conditions. The laser power and the pulse duration were the most important variables in determining the transient temperature profiles. The velocity of the liquid metal in the weld pool increased with time during heating and convection played an increasingly important role in the heat transfer. The peak temperature and velocity increased significantly with laser power density and pulse duration. At very high power densities, the computed temperatures were higher than the boiling point of 304 stainless steel. As a result, evaporation of alloying elements was caused by both the total pressure and the concentration gradients. The calculations showed that the vaporization occurred mainly from a small region under the laser beam where the temperatures were very high. Themore » computed vapor loss was found to be lower than the measured mass loss because of the ejection of tiny metal droplets owing to the recoil force exerted by the metal vapours. The ejection of metal droplets has been predicted by computations and verified by experiments.« less

72 citations


Journal ArticleDOI
TL;DR: In this paper, a dynamic spectral-method-based computer model of the induction skull melting (ISM) process was developed in close collaboration with the University of Birmingham, where extensive melting trials have been undertaken.
Abstract: Induction skull melting (ISM) is a widely used process for melting certain alloys that are very reactive in the molten condition, such as those based on Ti, TiAl, and Zr, prior to casting components such as turbine blades, engine valves, turbocharger rotors, and medical prostheses. A major research project has been undertaken with the specific target of developing improved techniques for casting TiAl components. The aims include increasing the superheat in the molten metal to allow thin section components to be cast, improving the quality of the cast components and increasing the energy efficiency of the process. As part of this, the University of Greenwich (United Kingdom) has developed a dynamic, spectral-method-based computer model of the ISM process in close collaboration with the University of Birmingham (United Kingdom), where extensive melting trials have been undertaken. This article describes in detail the numerical model that encompasses the coupled influences of turbulent flow, heat transfer with phase change, and AC and DC magneto-hydrodynamics (MHD) in a time-varying liquid metal envelope. Associated experimental measurements on Al, Ni, and TiAl alloys have been used to obtain data to validate the model. Measured data include the true root-meansquare (RMS) current applied to the induction coil, the heat transfer from the molten metal to the crucible cooling water, and the shape of the semi-levitated molten metal. Examples are given of the use of the model in optimizing the design of ISM furnaces by investigating the effects of geometric and operational parameter changes.

64 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the degree of embrittlement induced by the liquid metal by tensile tests and found that the brittle fracture surface area increases with logarithm of the exposure time.
Abstract: For some solid metal–liquid metal couples that exhibit liquid metal embrittlement, penetration of the embrittling liquid metal along grain boundaries of the solid metal is observed. Penetration speed of liquid gallium into aluminum and that of mercury into silver and copper were measured by using thin evaporated films. The degree of embrittlement induced by the liquid metal was estimated by tensile tests. The tensile specimens were kept in contact with the liquid metal for various times of exposure, and then the embrittler was removed before the test. When the exposure time is short, no sign of embrittlement is observed. As the exposure time increases further, the brittle fracture surface area increases with logarithm of the exposure time. The results imply the existence of an incubation period, which is inversely proportional to the penetration speed of embrittling liquid metal.

62 citations


Journal ArticleDOI
TL;DR: Rapid in situ analysis of liquid metal melts under reduced ambient pressure by laser-induced breakdown spectroscopy (LIBS) using a transportable system and the influence of variations in the ambient pressure on the results is discussed.
Abstract: We report on rapid in situ analysis of liquid metal melts under reduced ambient pressure by laser-induced breakdown spectroscopy (LIBS) using a transportable system. LIBS denotes a method in which characteristic optical emission line intensities of excited species in laser-generated plasma plumes are used for a quantitative chemical analysis of target materials. It is a fast, noncontact method that can be carried out under various atmospheric conditions, allowing large working distances between the sample under investigation and the detection system. For these reasons, LIBS is applicable in particular for process control in metallurgy under reduced ambient pressure. This was demonstrated for two types of vacuum devices under production conditions at a steel mill. The results of these experiments, including calibration curves for Cr, Ni, and Mg in liquid steel, are presented. The influence of variations in the ambient pressure on the results of the LIBS analysis is discussed within the frame of a generalized shock-wave model for the expansion of the laser-induced plasma plume.

51 citations


Journal ArticleDOI
TL;DR: In this article, high-pressure high-temperature experiments have been carried out up to 25 GPa and 2200°C in a multianvil press on assemblages made of silicates and iron-silicon alloys.

47 citations


Journal ArticleDOI
TL;DR: Based on the embedded-atom method, a constant-pressure, constant-temperature molecular dynamics technique is applied to obtain an atomic description of glass formation process in eutectic Cu40Ag60 alloy.

47 citations


Patent
23 Dec 2004
TL;DR: Active cooling technologies such as thermoelectrics can be used to introduce thermal gain into a cooling system and, when employed in combination with forced flow liquid metal cooling loops, can provide an attractive solution for cooling high heat flux density devices and/or components as mentioned in this paper.
Abstract: Active cooling technologies such as thermoelectrics can be used to introduce thermal “gain” into a cooling system and, when employed in combination with forced flow liquid metal cooling loops, can provide an attractive solution for cooling high heat flux density devices and/or components. Total cooling power can be increased by employing multiple thermoelectric elements. Indeed, by employing modern semiconductor technologies, including e.g., thin-film technologies, thermoelectric elements may be cost-effectively employed and configured in large arrays.

Patent
Ioan Sauciuc1, Gregory M. Chrysler1
13 Aug 2004
TL;DR: A liquid metal thermal interface for an integrated circuit die is discussed in this paper, where a liquid metal is used to transfer heat from the die to the heat transfer element, such as a heat spreader or heat sink.
Abstract: A liquid metal thermal interface for an integrated circuit die. The liquid metal thermal interface may be disposed between the die and another heat transfer element, such as a heat spreader or heat sink. The liquid metal thermal interface includes a liquid metal in fluid communication with a surface of the die, and liquid metal moving over the die surface transfers heat from the die to the heat transfer element. A surface of the heat transfer element may also be in fluid communication with the liquid metal. Other embodiments are described and claimed.

Journal ArticleDOI
TL;DR: In this paper, a heat treatment of liquid metal was initiated to investigate the possibility of removing oxide films and primary intermetallics from aluminium melts and its effectiveness, and the concept was to remove oxide cracks from liquid metal by precipitation of primary α-Fe onto oxide films, causing them to sink under the weight of the particles.
Abstract: A novel approach, the heat treatment of liquid metal, was initiated to investigate the possibility of removing oxide films and primary intermetallics from aluminium melts and its effectiveness. The concept was to remove oxide cracks from liquid metal by precipitation of primary intermetallics onto oxide films, causing them to sink under the weight of the particles. The sedimentation of primary α-Fe particles was investigated at 600°C using an Al–11·1Si–0·4Mg alloy. The liquid metal quality was assessed by reduced pressure and pressure filtration tests. After sedimentation processing there is a clear improvement in liquid metal quality due to the sedimentation and separation of primary α-Fe particles, causing the removal of some oxide films from aluminium melts. Thus the heat treatment of liquid metal has the potential to improve liquid metal quality. Primary α-Fe phase seems to precipitate onto the wetted sides (i.e. the outer interfaces) of double oxide films. However, the gap between the two dry...

Journal ArticleDOI
TL;DR: Experiments with lithium limiters have now been conducted in the Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory as discussed by the authors, and the results showed significant reduction in both recycling and in impurity levels.

Journal ArticleDOI
X. Yang, X. Huang, X. Dai, John Campbell, J. Tatler 
TL;DR: In this paper, an algorithm, Oxide Film Entrainment Tracking (OFET, 2-D), has been developed, tested and validated for numerical modelling of the liquid aluminium flow and movement, fold over and entrapment of oxide films during the mould filling process of aluminium castings.
Abstract: Recent advances in understanding the filling process during casting have indicated that metal flow conditions play a key role in controlling the quality of the casting. Inappropriate filling of castings usually causes surface oxide films to be folded into the bulk liquid or broken as a result of a higher liquid metal kinematic energy, resulting in so-called 'entrainment damage'. These folded oxide film defects are entrained in aluminium alloy casting and significantly affect both static and fatigue reliabilities. In the present study, an algorithm, Oxide Film Entrainment Tracking (OFET, 2-D), has been developed, tested and validated for numerical modelling of the liquid aluminium flow and movement, fold over and entrapment of oxide films during the mould filling process of aluminium castings. The Volume of Fluid (VOF) method is employed to track the free surface of liquid metal flow. A kinematic approach has been utilised for modelling the movement and entrainment of the oxide films on the liquid...

Journal ArticleDOI
TL;DR: In this article, the authors examined the mechanical properties in liquid metals of the T91 martensitic steel, a candidate material for the window of an accelerating driven system (ADS), and examined the risk of liquid metal embrittlement and the accelerated fatigue damage by a liquid metal.

Journal ArticleDOI
TL;DR: In this paper, the magnetohydrodynamics (MHD) features associated with a free surface flow in a fusion-relevant magnetic field environment, and determine what LM-free surface flow option is most suitable for lithium divertor particle pumping and surface heat removal applications in a near-term experimental plasma device, such as NSTX.

Journal ArticleDOI
TL;DR: In this article, the surface compositions of liquid Li, Ga, Sn, and a Sn-Li alloy in vacuum were examined as a function of temperature, and it was shown that hydrogen atoms at thermal energies can adsorb on both Li and Ga, but not on Sn.

Journal ArticleDOI
TL;DR: In this article, the authors presented an approach to draw an embryo of the liquid-liquid (L-L) phase diagram for binary alloys above liquidus in the paper, expecting to guide metallurgy process so as to improve the properties of alloys.

Patent
03 Nov 2004
TL;DR: In this paper, an approach to enable cooling electronic components in computer systems using liquid metal as a coolant is presented, where liquid metal coolant extracts heat generated by an electronic component and flows to a heat exchanger where the heat is rejected into ambient air through force convection.
Abstract: Apparatus and method are provided to enable cooling electronic components in computer systems using liquid metal as a coolant. The liquid metal coolant extracts heat generated by an electronic component and flows to a heat exchanger where the heat is rejected into ambient air through force convection. A pump is used to enable the liquid metal coolant to circulate in a closed loop system.

Journal ArticleDOI
TL;DR: In this paper, the authors applied a rotating magnetic field (RMF) and a travelling magnetic field and recorded flow maps by means of ultrasonic Doppler velocimetry.
Abstract: This paper is concerned with laboratory studies using liquid metals with T melt ≤ 300°C to model the flow of metals in industrial processes. Considering three selected examples the main features of such cold models are described. In the first instance we examine an aluminium alloy investment casting process. The requirement of reducing high flow velocities was achieved by the application of a static magnetic field. Local velocity measurements as well as integrated flow rate determination were carried out using eutectic InGaSn (T melt = 10°C). Secondly, model experiments were performed on the electromagnetic stirring of liquid metals in a cylindrical cavity. We applied a rotating magnetic field (RMF) and a travelling magnetic field and recorded flow maps by means of ultrasonic Doppler velocimetry. With the goal of an efficient 3D-mixing, measurements were made using a combination of both field types with promising results. Thirdly, we report on systematic studies of the effect of an RMF on the solidification of a PbSn alloy. Directional solidification experiments demonstrate the influence of the electromagnetically driven convection on the resulting microstructure.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the issues in integrating a liquid surface divertor into a configuration based upon an advanced tokamak, specifically the ARIES-RS configuration, where the simplest form of such a divertor is to extend the flow of the liquid first wall into the divertor and thereby avoid introducing additional fluid streams.

Journal ArticleDOI
TL;DR: Such heavy coolants as lead and a eutectic alloy of lead with bismuth while having favorable thermophysical and technological properties are comparatively corrosive for structure materials and can be contaminated by solid impurities during the operation of the system as mentioned in this paper.
Abstract: Such heavy coolants as lead and a eutectic alloy of lead with bismuth while having favorable thermophysical and technological properties are comparatively corrosive for structure materials and can be contaminated by solid impurities during the operation of the system.

Patent
02 Mar 2004
TL;DR: In this article, a method for making porous aluminum product and products therefrom and, in particular, a method of rapidly solidifying a liquid metal foam produced by the incorporation of gas forming agents into an aluminum melt.
Abstract: The present invention is directed to a method for making porous aluminum product and products therefrom and, in particular, a method of rapidly solidifying a liquid metal foam produced by the incorporation of gas forming agents into an aluminum melt. The aluminum melt may be stabilized to support the creation of liquid metal foam by the addition of metal and/or ceramic additives. The decomposition of the gas forming agents and subsequent expansion of the gaseous products is controlled through the use of a reactor, wherein temperature, pressure and transit time can be adjusted to match the decomposition kinetics of the gas forming agent. The invention allows for the economical production of liquid metal foam of uniform cell size that can be continuously cast into sheet, plate and profile sections. Such metal foam products may be used in structural, thermal and acoustic applications.

Patent
20 Apr 2004
TL;DR: In this paper, the surface tension of the liquid metal will exceed its hydrostatic pressure against the piston, thus forming a leak-tight seal, and the metal will not flow past the piston seal if a suitably small gap is formed between the piston and the reservoir walls.
Abstract: A liquid metal evaporation source for use in Molecular Beam Epitaxy and related metal vacuum deposition techniques. An evaporator is maintained at a high temperature to evaporate a liquid metal, a reservoir for holding the liquid metal source is maintained at a temperature above the melting point of the metal but below the temperature in the evaporator, and a hollow transport tube connecting the evaporator and reservoir is maintained at a temperature between these temperatures. The reservoir is in the shape of a hollow cylinder with a close-fitting cylindrical piston which is used to force the liquid metal through the hollow transport tube into the evaporator. The liquid metal will not flow past the piston seal if a suitably small gap is formed between the piston and the reservoir walls wherein the surface tension of the liquid metal will exceed its hydrostatic pressure against the piston thus forming a leak-tight seal.

Journal ArticleDOI
TL;DR: To investigate the effect of the recirculation flow on the bubble behavior, visualization and measurement of nitrogen gas-molten lead bismuth in a rectangular tank was performed by using neutron radiography and particle image velocimetry techniques.

Journal ArticleDOI
TL;DR: In this paper, the erosion of liquid-metals from low-energy particle bombardment at 45° incidence has been measured for a combination of species and target materials in the ion-surface interaction experiment (IIAX) at the University of Illinois Urbana-Champaign.

Journal ArticleDOI
TL;DR: In this article, a nanosized mechanocomposites were prepared for Cu-Bi and Fe-Bi systems, and the content of Bi in these systems must be lower than 3 at.
Abstract: Mechanical alloying is the most perspective method for preparation of nanosized mechanocomposites in non-mixed liquid and solid metals. It is known that plastic metals get fragile in the presence of the liquid metal phase, and this phase spreads over the surface of solid metal due to good wettability. Temperature of milling bodies can rise by several hundred degrees in the high-energy planetary ball mill. Low melting metals, such as gallium, indium, tin, and bismuth can melt on the surface of the balls. So, a pair composed of liquid and solid metal can form in an activator. In such cases, it can be assumed that mechanical activation of metal systems with positive mixing enthalpies, can allow forming a morphologically metastable structure with unusually high concentration of inter-phase boundaries due to easy-melting component spreading along the boundaries of particles formed by comminution of the solid component. Nanosized mechanocomposites were prepared for Cu-Bi and Fe-Bi systems. The content of Bi in these systems must be lower than 3 at. (10 wt.)%. The obtained mechanocomposites represent nanosized particles of copper (or iron) coated with a layer of bismuth in 2-3 atoms. Mechanical activation of the formed composites leads to the formation of supersaturated solid solutions.

Journal ArticleDOI
Yanning Zhang1, Li Wang1, Weimin Wang1, Xiangfa Liu1, Xuelei Tian1, Peng Zhang1 
TL;DR: In this paper, a molecular dynamics simulation within the framework of empirical tight-binding potential on the liquid structure of Au under different pressures during the rapid cooling process is presented, where pair correlation function (PCF) and the pair analysis (PA) technique are used to reveal the structural characteristics of liquid Au under normal and high pressures.

Journal ArticleDOI
TL;DR: It is shown that a uniform longitudinal magnetic field significantly reduces amplitudes and velocities of surface instabilities and is able to stabilize the jet during period of time typical for the jet breakup at zero magnetic field.