The rheological behavior of semisolid aluminium alloy (A356) slurry is investigated by
using a concentric cylinder viscometer under high cooling rate (30 to 50°C/min) and high shear rate
(650 to 1500s-1) conditions. Two different series of experiments are carried out. In all of these
experiments, the pellets of A356 alloy are poured into the outer cylinder where they melt completely
by resistance heating. When the inner cylinder is placed concentrically, the molten metal resides in
the annular space between the cylinders. As the inner cylinder rotates, the alloy is sheared
continuously during cooling from a temperature of 630°C, and a slurry forms. In the first series of
experiments, for different cooling rates, shearing continues under a constant shear rate until rotation
of the inner cylinder stops. During experiments, the temperature of the slurry is measured
continuously using a K-type thermocouple, from which the solid fraction is calculated. In the second
series of experiments, the molten alloy is cooled and sheared continuously at different shear rates
for a given cooling rate. The apparent viscosity of the slurry is calculated by measuring the torque
applied to the inner cylinder and its rotational speed. The results show that the slurry viscosity
increases with increasing fraction of solid and increasing cooling rate, and it decreases with
increasing shear rate. At high values of shear and cooling rates, the viscosity varies gradually up to a
solid fraction of about 0.5.
Statistical Relationship Between Strontium Content and Cooling Rate on A356 Alloy by Using Regression Analysis
