SHEAR RATE THICKENING FLOW BEHAVIOR OF SEMISOLID SLURRIES

The constitutive flow behavior of semisolid slurries is a strong function of temperature and prior processing history. The history dependence of this constitutive behavior lends itself to modeling via an internal variable framework that separates the evolution of structure from the flow behavior at a constant structure. We have assembled a computer-controlled, high-temperature Couette rheometer and have characterized the constant structure constitutive behavior of a tin-15 pct lead system from 0.3 to 0.45 fractions solid. The flow behavior at a given material structure is shear rate thickening and not shear rate thinning, as is commonly assumed.