Jürgen Brillo

Reference Data for the Density and Viscosity of Liquid Aluminum and Liquid Iron

The available experimental data for the density and viscosity of liquid aluminum and iron 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 proposed standard reference correlations for the density of the aluminum and iron are characterized by standard deviations of 0.65% and 0.77% at the 95% confidence level, respectively. The overall uncertainty in the absolute values of the density is estimated to be one of ±0.7% for aluminum and 0.8% for iron, which is worse than that of the most optimistic claims but recognizes the unexplained discrepancies between different methods. The standard reference correlations for the viscosity of aluminum and iron are characterized by standard deviations of 13.7% and 5.7% at the 95% confidence level, respectively. The uncertainty in the absolute values of the viscosity of the two metals is thought to be no larger than the scatter between measurements made with different techniques and so can be said to be ±14% in the case of aluminum and ±6% in the case of iron.

Density Determination of Liquid Copper, Nickel, and Their Alloys

A method for the determination of the density of electromagnetically levitated metallic liquids has been developed. This method employs an enlarged beam of parallel laser light to produce a shadow image of the sample. The shadow is recorded by a digital CCD-camera, and the images are analyzed using an edge detection algorithm. The circumference is fitted by Legendre polynomials that can be used for calculations of the volume of the sample. The method has been tested successfully on various alloys of copper-nickel (NixCuy), as well as on the pure elements, Cu and Ni. Densities were measured for each sample at different temperatures below and above the melting point, and a linear behavior was observed. At the melting point the densities for copper and nickel were 7.9 and 7.93g⋅cm−3, respectively. For T=1270°C liquid copper has a density of 7.75g⋅cm−3 which strongly increases up to roughly 8.1g⋅cm−3 if a small amount (10–40 at.%) of nickel is added to the system. For nickel concentrations larger than 50at.% the density remains nearly constant.

Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

Abstract 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 forming ability and chemical short-range ordering in liquid Al – Fe and Al – Ni alloys.

Density and excess volume of liquid copper, nickel, iron, and their binary alloys

Abstract The densities of liquid copper, nickel and iron and their binary alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of electromagnetic levitation and optical dilatometry. In all cases the density was a linear function of temperature. On the other hand, the concentration dependence was only linear for Fe–Ni, whereas Fe–Cu and Cu–Ni are characterized by a positive or negative excess volume respectively.

Density and thermal expansion of liquid binary Al–Ag and Al–Cu alloys

Abstract 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 concentration dependence of density and thermal expansion was studied for both systems. It was found for Al–Ag and Al–Cu that both density and thermal expansion can be related to a negative excess volume and its temperature coefficient.

Surface tension of liquid Al–Cu binary alloys

Abstract 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 the entire range of composition and precise data were obtained in a broad temperature range. It was found that the surface tensions can be described as linear functions of temperature with a negative slope. Moreover, they monotonically decrease with an increase in the aluminium concentration. The observed behaviour with respect to both temperature and concentration is in agreement with thermodynamic model calculations using the subregular solution approximation.

Thermophysical property measurements of liquid metals by electromagnetic levitation

Electromagnetic levitation is a useful technique for containerless processing of liquid metals. In combination with non-contact diagnostic tools it can be used for completely non-invasive measurements of thermophysical properties of metallic melts. Considerable progress has been made in this field in recent years. This paper reviews methods and results, including those obtained in microgravity.

Density and viscosity of ternary Al–Cu–Si liquid alloys

Densities and viscosities of ternary Al–Cu–Si liquid alloys have been investigated over a wide temperature and composition range. Density was measured using electromagnetic levitation as a container-less technique, while viscosity was measured by means of a high-temperature oscillating cup viscometer. In this ternary system, binary interaction parameters as well as a third (ternary) interaction parameter need to be taken into account for the excess volume to describe the liquid densities. The temperature dependences of the viscosities are well described by the Arrhenius law. A maximum of the activation energy of viscous flow is found in that compositional range in which intermetallic phases exist in the solid state.

Viscosity measurement of liquid ternary Cu–Ni–Fe alloys by an oscillating cup viscometer and comparison with models

Abstract 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 exponential Arrhenius law, taking into account an activation energy for the viscous flow. The activation energies for the ternary alloys were found to be linear combinations of the corresponding activation energies of the pure elements Cu, Ni, and Fe. At constant temperature, a non ideal mixing behaviour was observed and the data were compared with several quantitative models. Close agreement of the experimental results was found with the predictions of two models by Kaptay and Hirai.

Viscosity of liquid Co–Sn alloys: thermodynamic evaluation and experiment

Shear viscosity measurements were performed for liquid Co–Sn alloys over a wide temperature range above the respective liquidus temperatures. A high temperature oscillating-cup viscometer was used. It was found experimentally that viscosity as a function of temperature obeys an Arrhenius law. The data were compared with calculated values, obtained from different thermodynamic approaches. A good agreement was found between experimental results and calculated ones by the Budai–Benkö–Kaptay model.