Thermophysical properties of Si, Ge, and Si-Ge alloy melts measured under microgravity

We have investigated density, thermal expansion, and surface tension of Si, Ge, and Si-Ge alloys in the melt and undercooled state under microgravity conditions. The experiments were conducted in the TEMPUS facility on board a Zero-G aircraft. The density of the liquid alloys as a function of composition show a nonideal behavior. Thermal expansion coefficients were found to be in the order of 10 − 4 K − 1 and was highest for Si 75 Ge 25 melt. The surface tension is lowered with the addition of 25 at. % Si in Ge. The further addition of Si increases the surface tension almost linearly with composition.