How to measure viscosity of liquid aluminum alloys?

Viscosity of liquid Al and Al-Si alloys are critical to better understand the solidification and porosity formation in the mushy zone towards the end of solidification of the alloy. In this paper, viscosity data from the literature for Al and Al-Si alloys are presented along with the drawbacks of the most prevalent technique used to evaluate viscosity - the oscillating vessel viscometer. Experimental techniques using an alternative rotational rheometer equipped with a cone and plate measuring geometry are presented along with results of flow characterization of molten Zn and Al-Si alloys. The results show that molten Zn exhibits Newtonian flow characteristics and molten Al-Si eutectic alloy exhibits a non-Newtonian behavior at various melt superheats and low shear rate regimes.