Thermophysical Properties of Liquid Aluminum

Abstract

Ohmic pulse-heating with sub-microsecond time resolution is used to obtain thermophysical properties for aluminum in the liquid phase. Measurement of current through the sample, voltage drop across the sample, surface radiation, and volume expansion allow the calculation of specific heat capacity and the temperature dependencies of electrical resistivity, enthalpy, and density of the sample at melting and in the liquid phase. Thermal conductivity and thermal diffusivity as a function of temperature are estimated from resistivity data using the Wiedemann-Franz law. Data for liquid aluminum obtained by pulse-heating are quite rare because of the low melting temperature of aluminum with 933.47 K (660.32°C), as the fast operating pyrometers used for the pulse-heating technique with rise times of about 100 ns generally might not be able to resolve the melting plateau of aluminum because they are not sensitive enough for such low temperature ranges. To overcome this obstacle, we constructed a new, fast pyrometer sensitive in this temperature region. Electromagnetic levitation, as the second experimental approach used, delivers data for surface tension (this quantity is not available by means of the pulse-heating technique) and for density of aluminum as a function of temperature. Data obtained will be extensively compared to existing literature data.

Tabular electrical conductivity for aluminium

“…The new table is compared with that of experiments in the liquid regime in Figure 6. These data have recently been confirmed by Leitner et al [47] Also shown are DFT-MD results by Witte et al [40] The new table agrees well with the PBE calculations, as expected, since it was constructed to match our own PBE calculations in this regime (but not these exact points). The table and the PBE results overestimate the data.…”

“…(Colour online) Solid aluminium resistivity. Shown are experimental points by Brandt and Neuer and a recent set of measurements from Leitner et al, where we have shown the fit given in their paper and the density runs from 2.53 to 2.63 g/cm 3 for the line shown. Two adjacent isochores from the new table are shown (2.7 and 2.4 g/cm 3 ) that should, if the table is accurate, bracket the experimental data.…”

“…In the solid regime (Figure ) we have used the same model as given by Yim . The adjustable parameter in that model is tuned to match the data given by Desai et al The melt line is tuned to fit the experiment by Leitner et al Note that no special consideration is given to the solidus–liquidus region, or to the liquid‐vapour coexistence region. The model by Yim is simply used below T melt , and above T melt , the DFT‐based model is used.…”

“…The model by Yim is simply used below T melt , and above T melt , the DFT‐based model is used. In Figure , we show a comparison of the new table to the experiments by Leitner et al and Brandt and Neuer . To avoid interpolation artefacts, we have shown the two isochores that should bracket the data (which account for thermal expansion).…”

“…[46] These data have recently been confirmed by another experiment. [47] Also shown are DFT-MD results of Witte et al [40] The line connecting the Sesame 23715 points serves only as a guide to the eye.…”