Rotational rheometry of liquid metal systems: Measurement geometry selection and flow curve analysis

In the present study, a rotational measurement technique was used to evaluate viscosities of liquid metals and metallic alloys. Three types of measurement geometries in a high temperature rotational rheometer were evaluated: cone and plate, DIN coaxial, and double concentric cylinder (DCC). The DCC geometry proved to be the most effective. An analytical solution has been presented to evaluate the viscosity as a function of shear rate for DCC geometry. The flow curves and shear viscosities of pure Al, pure Zn and Sn95.8Ag3.28Cu0.92 solder alloy have been evaluated as a function of shear rate and melt superheat temperature. It is proposed that liquid metal systems are non-Newtonian and strongly shear thinning in flow behavior.