Contactless measurement of temperaturedependent viscosity and surface tension of liquid Al69.1Cu12.8Ag18.1 eutectic alloy under microgravity conditions using the oscillating-drop-method

Abstract

Thermophysical properties of the Al69.1Cu12.8Ag18.1 eutectic liquid alloy are of particular interest for support of self-and inter-diffusion studies. In the presented work, Al69.1Cu12.8Ag18.1-samples were processed contactlessly by electromagnetic levitation under microgravity conditions using the TEMPUS facility. The measurements were performed onboard the Airbus A310 Zero-G in parabolic flight campaigns. The oscillating-drop-method (ODM) was used for measurements of the viscosity via oscillations damping and surface tension via oscillations frequency. These were determined for temperatures in the range of 900–1500 K by analysis of the oscillation spectrum obtained from the electrical impedance. The latter was measured using the Sample Coupling Electronics. An Arrhenius-law η(T) ∝η∞ exp(Eη /RT) was used to fit the temperature-dependent viscosity data. The resulting fit parameters were η∞ = (0.632±0.160) mPas and activation energy of viscous flow Eη = (2.344±0.233) · 104 J/mol. A linear law γ(T) = γl + γT (T - Tm) was fit to the surface tension data yielding γl = (0.9013±0.02625) Nm−1 and γT = −(0.7462±0.2675)·10−4 Nm−1 K−1. The Kozlov-model was applied to determine the enthalphy of mixing as ΔHmix = -(18.576±0.018)kJ/mol.