Ivan Egry

• Professor Dr.
• German Aerospace Center (DLR)

The densities of liquid copper, cobalt, and iron, their binary and ternary alloys have been measured over a temperature range including the undercooled regime. A non-contact technique was used, consisting of electromagnetic levitation combined with optical dilatometry. For all samples, the density was a linear function of temperature. The concentra...

The idea of proposing a series of dedication papers to honour Prof. Ismail Tavman in this journal naturally arose from the discussions among invited speakers and organizing committee, and was promptly supported by the journal Editors, Profs. Egry and Sacadura. This opportunity was then open to the participants, and a committee was formed to aid in...

The present study is an overview of the surface properties of liquid Al-Ni alloys, which are of great importance for the design and development of new Al-Ni and Ni-based industrial alloys, widely used as functional and structural materials. The solidification and thus, the microstructural evolution are directly dependent on the interface / surface...

For the study of the interaction of a liquid alloy with differently oriented single crystalline sapphire surfaces precise surface tension data of the liquid are fundamental. We measured the surface tension of liquid Al-Cu contactlessly on electromagnetically levitated samples using the oscillating drop technique. Data were obtained for samples cove...

The coexistence of a liquid with a solid and a gas phase causes a contact angle at the triple line and results in a certain work of adhesion. These properties were studied for liquid Al, Cu, and their alloys on single-crystalline sapphire surfaces with C(0001)-, A(11-20)-, and R(1-102)- orientation. Measurements were performed at 1100 °C and under...

This chapter discusses the structure and properties of molten metals. First, an introduction into current theories of their structure is given. Then the relevant functions used to characterize liquid structure, i.e., pair-correlation functions and structure factors are discussed and experimental techniques to determine them are presented. Special e...

Starting from Butlers equation, an explicit expression for the excess surface tension of a binary alloy is derived. First, the case of ideal solution is treated within the weak segregation limit. Then, interactions are included through the partial excess Gibbs enthalpies for regular solutions. The derived expressions allow the study of the interpla...

Levitation melting is a containerless technique requiring non-contact diagnostic tools. In order to properly perform such experiments, a precise knowledge of the heat balance between inductive heating of the sample and the heat losses due to radiation and heat conduction is a prerequisite. This paper provides the necessary theoretical background an...

In the present work a high temperature oscillating cup viscometer has been used to measure the viscosities of liquid binary Al–Cu alloys. The dependence of viscosity on temperature is well described by the Arrhenius law. For constant temperature, the viscosity as a function of copper concentration exhibits a maximum at a mole fraction x Cu = 0.7. T...

The density of Al-rich liquid Al–Si alloys was measured contactlessly on electromagnetically levitated samples using optical dilatometry. Data were obtained for samples covering compositions up to 50 at.% Si and in a temperature range between 650 and 1500 °C. The densities can be described as linear functions of temperature with negative slopes. Mo...

The oscillation spectrum of a compound drop, consisting of two immiscible liquids, one constituting a liquid central core, surrounded by a liquid layer of the second liquid, resembles that of two coupled harmonic oscillators. From frequency analysis it is possible to determine the surface tension of the outer liquid, and the interfacial tension bet...

The density of Al-rich liquid Al–Si alloys was measured contactlessly on electromagnetically levitated samples using optical dilatometry. Data were obtained for samples covering compositions up to 50 at.% Si and in a temperature range between 650 and 1500 °C. The densities can be described as linear functions of temperature with negative slopes. Mo...

The available experimental data for the density and viscosity of liquid cadmium, cobalt, gallium, indium, mercury, silicon, thallium, and zinc have been critically examined with the intention of establishing both a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality...

Results of a thermophysical characterization of a Fe-Cr-Mo alloy in the solid and liquid state are reported. Methods applied include calorimetry, dilatorimetry; the laser flash technique for theraml diffusivity, and ultrasound pulse echo for the measurement of the room temperature sound velocities and elastic constants. Density in the liquid phase...

Results of a thermophysical characterization of a Fe-Cr-Mo alloy in the solid and liquid state are reported. Methods applied include calorimetry, dilatorimetry; the laser flash technique for theraml diffusivity, and ultrasound pulse echo for the measurement of the room temperature sound velocities and elastic constants. Density in the liquid phase...

ISPS is the major international scientific forum for researchers in physics utilizing the space environment, in particular microgravity. It is intended to inspire and encourage cross-cutting discussions between different scientific communities working in the same environment. Contributions discussing results of experiments carried out on drop tower...

The viscosity of eutectic PdSi alloys has been measured by different techniques. The conventional oscillating cup viscosimetry was used in the ground-based laboratory, while the oscillating drop technique was applied in a microgravity experiment. Different working equations were utilised to derive the viscosity from the damping of the oscillations,...

The viscosity of eutectic PdSi alloys has been measured using different techniques. Conventional oscillating cup viscosimetry was used in the ground-based laboratory, while the oscillating drop technique was applied in a microgravity experiment. Different working equations were utilised to derive the viscosity from the damping of the oscillations,...

A significant amount of time and costs could be saved on the development of new materials through numerical modeling, if there was an understanding on how their thermophysical properties change with a change of composition. Here, we report on systematic measurements of the density for a number of liquid metallic alloys. These measurements were carr...

The available experimental data for the density and viscosity of liquid antimony, bismuth, lead, nickel and silver have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a ser...

The available experimental data for the density and viscosity of liquid antimony, bismuth, lead, nickel and silver have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a ser...

The surface tension of liquid Cu-Ti alloys the containerless technique of electromagnetic levitation and theoretically calculated in the framework of the compound formation model. Measurements have been carried out on alloys covering the entire range of composition and over the temperature range 1275 K - 2050 K. For all investigated alloys, the sur...

The analysis of surface oscillations of liquid drops allows measurements of the surface tension and viscosity of the liquid. For small oscillations of spherical drops with a free surface, classical formulae by Rayleigh and Lamb relate these quantities to the frequency and damping of the oscillations. In many cases, however, the drop's surface is co...

The surface tension of an industrial FeC-alloy containing Si, Mn and S in the few atomic per cent range was measured by the oscillating drop method in ground based electromagnetic levitation and under reduced gravity conditions on board a parabolic flight. The results from the parabolic flight exhibited a large variation between different heating c...

In recent years, levitation methods have been increasingly used to study the atomic structure and dynamics of high-temperature liquids, in particular metallic melts. These methods provide a containerless and, consequently, high-purity sample environment. No corrections for signals due to a crucible need to be made, and deep undercoolings of the liq...

Surface tension is the common denominator for all three M's of the title. Its spatial variation is responsible for surface tension driven Marangoni convection. Of equal importance for the surface tension of liquid metals is the role of surface active elements, a topic which has occupied a major portion in the professional career of Prof. Mills and...

In this report, a survey is presented about state-of-the-art thermophysical property measurements of liquid metallic alloys at high temperatures. Methods for measuring both caloric quantities, like specific heat and thermal conductivity, and thermophysical properties, like density, surface tension and viscosity, are described in detail. Measurement...

Electromagnetic lévitation is a useful technique for containerless processing of liquid metals. In combination with non-contact diagnostic tools it can be used for measurements of thermophysical properties of metallic melts. This paper reviews the measurement methods used on ground and in microgravity.

In recent years, levitation methods have been increasingly used to study the atomic structure and dynamics of high-temperature liquids, in particular metallic melts. These methods provide a containerless and, consequently, high-purity sample environment. No corrections for signals due to a crucible need to be made, and deep undercoolings of the liq...

This paper reviews investigations by the authors on thermophysical properties and solidification behaviour of liquid metals. Containerless processing techniques, such as electromagnetic levitation as well as adiabatic aerogel furnaces have been used to study properties of the equilibrium and undercooled melt as well as near and non equilibrium soli...

Molecular dynamics computer simulations of various symmetrical Lennard-Jones (LJ) models are used to elucidate how the excess volume in dense binary liquids is related to the microscopic interactions between the particles. Both fully miscible systems and systems with a liquid-liquid phase separation are considered by varying systematically the para...

The use of electromagnetic levitation for containerless processing of liquid metals dates back into the thirties of the last century. Its use for thermophysical property measurements started in the sixties. Later on, in the nineties, the possibility to perform such experiments under microgravity boosted this research field. Although a number of mic...

The electromagnetic levitation technique (EML) has been successfully employed in order to levitate Cu-Ti binary alloys. A digital CMOS-camera (400 fps) recorded image sequences of oscillating liquid sample and surface tension has been determined by oscillating drop method from the analysis of the frequency spectra. Measurements have been performed...

In steelmaking, thermophysical properties like viscosity, density and surface tension are important quantities and of great practical interest. In the present paper the surface tensions of binary NiCr alloys have been calculated as functions of composition using the Gibbs energy minimisation method. Simultaneously, surface tensions have been measur...

Surface tension data of liquid Al–Cu–Ag ternary alloys have been measured contactlessly using the technique of electromagnetic levitation. A digital CMOS-camera (400 fps) recorded image sequences of the oscillating liquid sample and the surface tension was determined from an analysis of the frequency spectra. Data were obtained at temperatures abov...

Surface tension measurements are a central task in the study of surfaces and interfaces. For liquid metals, they are complicated by the high temperatures and the consequently high reactivity characterising these melts. In particular, oxidation of the liquid surface in combination with evaporation phenomena require a stringent control of the experim...

The available experimental data for the density and viscosity of liquid copper and tin have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The propose...

The surface tension and density of three liquid AlTi-based alloys (AlTiV, AlTiNb, and AlTiTa) have been measured using electromagnetic levitation as a tool for containerless processing. Surface tension has been determined by the oscillating-drop method, while the density was measured using a shadowgraph technique. Both quantities were determined ov...

Within the Integrated Project IMPRESS, funded by the EU, a concerted action was taken to determine the thermophysical properties of a c-TiAl-based alloys, suitable for casting of large turbine blades for aeroengines and stationary gas turbines. The challenge was to develop a castable alloy, free of grain refiners and susceptible to heat treatment....

Precise surface tension data of liquid Cu are fundamental for studying its interaction with differently oriented single crystalline sapphire surfaces. For this reason, the surface tension of liquid Cu was measured covering a wide temperature interval of 1058°C≤T≤1413°C. To avoid contamination of the sample from contact with container walls, the mea...

Surface segregation is very important for understanding the surface tension of binary systems. In case of a regular solution, the surface segregation is calculated using the Butler model. However, in the case of a complex system, like those forming intermetallic compounds, it is difficult to express the surface segregation. In order to discuss surf...

Using electromagnetic levitation under microgravity conditions, the interfacial properties of an Cu75Co25 alloy have been investigated in the liquid phase. This alloy exhibits a metastable liquid miscibility gap and can be prepared and levitated in a configuration consisting of a liquid cobalt-rich core surrounded by a liquid copper-rich shell. Exc...

Within the Integrated Project IMPRESS, funded by the EU, thermophysical properties of two Al-Ni alloys have been investigated: Raney-nickel (Al-31.5at%Ni) and Al-25at%Ni, corresponding to the intermetallic phase Al3Ni. Transition temperatures, latent heat, heat capacity, density and electrical resistivity were measured in the solid and liquid phase...

Thermophysical property measurements of high-temperature liquids are difficult and challenging. The microgravity environment offers substantial advantages for such measurements as compared to terrestrial laboratories. On the one hand, it allows containerless processing of these materials by suitable electromagnetic or electrostatic levitation techn...

Surface tension data of liquid Al–Cu binary alloys have been measured contactlessly using the technique of electromagnetic levitation. A digital CMOS-camera (400 fps) recorded image sequences of the oscillating liquid sample and surface tensions were determined from analysis of the frequency spectra. Measurements were performed for samples covering...

Reliable thermophysical data form the basis of any accurate solidification simulation. For the liquid phase of high-temperature metallic alloys, such data are scarce. In recent years, containerless methods, in particular electromagnetic levitation, have paved the way for noncontact measurement methods allowing precise determination of crucial therm...

In this paper, measurements of the heat capacities and thermal diffusivities of commercial CMSX-4 nickel-based superalloy are described, and the results are presented. Since the as-received commercial alloy sample is not at the thermodynamic equilibrium state, the phases present in the alloy undergo transformations toward equilibrium state as the m...

Within the Coolcop project, funded by ESA, the thermophysical properties of selected liquid Cu-Co-Ni alloys were investigated. Using the new high-temperature oscillating cup viscometer at DLR, the viscosity of this alloy along two perpendicular cuts in the ternary phase diagram was measured as a function of temperature. Along the same cuts also sur...

The density, thermal expansion coefficients, and surface tension of a number of liquid binary and ternary alloy systems were measured systematically. As noncontact technique a electromagnetic levitator was used for optical densitometry and oscillating drop tensiometry. At temperatures above and below the liquidus point, the density and surface tens...

In the present study, we compare available experimental surface tension data with two theoretical concepts: the Butler equation and a multilayer model in which the surface is described as a stacking of atomic layers. The experimental data were measured systematically over a wide temperature and concentration range using electromagnetic levitation a...

Materials sciences provide the basis for most modern technologies, for example, IT and photovoltaics, aerospace and automotive applications, nanoand biotechnology, just to name a few. In recent years, the trend in developing new products moved from the conventional try-and-error approach to computer-based modeling. This has become possible due to t...

In a systematic study, the surface tensions of the binary alloys Al–Fe and Al–Ni were investigated over a wide temperature and concentration range using electromagnetic levitation and the oscillating drop technique. Surface tensions were derived from the oscillation frequencies applying the formalism of Cummings and Blackburn. Temperature was measu...

The chemical short-range structure was studied in liquid Al-Ni alloys by x-ray absorption spectroscopy as a function of temperature and composition. A containerless technique, combining aerodynamic levitation and inductive heating, was used to position and melt the samples. The fluorescence yield x-ray absorption at the Ni K edge was measured by a...

or a wide range of new products in the industrial production chain, solidification processing of metallic alloys from the melt is a step of uppermost importance. Such advanced products are usually complex and made up of many components. Examples are: • turbine blades for land-based power plants and for jet engines sustaining high temperatures and h...

The thermal diffusivities of some industrially important alloys have been measured as a part of the EU funded Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project which is coordinated by the European Space Agency (ESA). The thermal diffusivities of the alloys were measured by the Laser flash method with...

Densities and thermal expansion coefficients of liquid Al–Ag and Al–Cu alloys were measured using the technique of electromagnetic levitation. This technique involves producing shadow images of the sample from which the volume is calculated by an image processing algorithm. Data was obtained at temperatures above the melting point. The concentratio...

In this paper, we report on density and viscosity measurements of liquid Al-Cu-Ag alloys. The densities have been measured on electromagnetically levitated samples by a shadowgraph technique. The viscosities were obtained by means of an oscillating cup viscometer where a suspended crucible containing the liquid sample performs torsinal oscillations...

The binary system Al-Ni is a base of a whole class of materials called superalloys. Although widely used for high temperature applications, the thermophysical properties of this system are rather unknown due to experimental difficulties. To provide such data the viscosity of the liquid binary alloy Al-Ni has been measured at temperatures up to 2073...

A new oscillating cup viscometer for temperatures up to 2,300�C has been constructed. A vacuum furnace with a graphite heater is used for heating the sample. The temperatures of the furnace and sample are measured by both a thermocouple and a pyrometer. The temperature is controlled with a stability better than 1 K. The oscillation of the cup is me...

In the framework of its 6th Framework Programme, the European Union funds the Integrated Project IMPRESS, related to industrial applications of Ti–Al and Ni–Al alloys. One central task of this project is the precise determination of the relevant thermophysical properties of selected alloys for both the solid and liquid phases. The properties to be...

The density and surface tension of Cu–Co–Fe alloys have been measured using the non-contact technique of electromagnetic levitation. At temperatures above and below the liquidus point, the density and surface tension are linear functions of temperature. The experimental density results can be predicted by means of the regular solution model from th...

Viscosity data on Cu – Ni – Fe have been obtained using an oscillating cup viscometer. In this method, a liquid sample is suspended in a crucible which performs damped angular oscillations. Viscosities are calculated from the time period and the decay of the amplitude. The temperature dependence of the measured viscosities can be described by an ex...

The density of liquid Al-Fe and Al-Ni binary alloys have been determined over a wide temperature range by a non-contact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound fo...

Density and surface tension of liquid Ni-Cu-Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator, an optical densitometer and an oscillating drop tensiometer. At temperatures above and below the liquidus point, density and surface t...

The densities of liquid copper, cobalt, and iron, their binary and ternary alloys have been measured over a temperature range including the undercooled regime. A non-contact technique was used, consisting of electromagnetic levitation combined with optical dilatometry. For all samples, the density was a linear function of temperature. The concentr...

The local short-to-intermediate range structure was studied in liquid Al-Ni and Al-Cu alloys by X-ray diffraction as a function of temperature and composition. A containerless technique, combining aerodynamic levitation and inductive heating, was used to position and melt the samples. The scattered intensity was recorded by an image plate. Liquid s...

Thermophysical properties of liquid multicomponent alloys J. Brillo, I. Egry Deutsches Zentrum f. Luft- und Raumfahrt, Institute of Space Simulation, D-51170 Koeln, Germany 1. Purpose The study of thermophysical properties of liquid metals is not only important for the simulation of certain industrial manufacturing processes, it also reveils insig...

Since the beginning of materials science research under microgravity conditions immiscible alloys have been an interesting subject. New possibilities to investigate such systems are offered by containerless processing techniques. Of particular interest is the ternary system Cu-Fe-Co, and its limiting binaries, Cu-Co and Cu-Fe. They all show a metas...

For measurements of the surface tension the oscillating drop technique is employed. With the help of digital image processing this method yields the frequencies of the surface oscillations from which the values of the surface tension can be derived. In the framework of ESA’s Thermolab project, the surface tensions of two representative steels: one...