Effect of Chemical Composition on Apparent Viscosity of Semisolid Alloys

Abstract

Stirring experiments of Al, Cu and Fe-based semi-solid alloys on continuous cooling were carried out to investigate the effect of chemical composition on the apparent viscosity of semi-solid alloy slurries. The apparent viscosity for these alloys increased with increasing solidification rate and decreasing shear rate, and the critical fraction of solid for fluidity increased with decreasing solidification rate and increasing shear rate. The equation for apparent viscosity ηa of semi-solid alloy was proposed as follows:[formula-omited] where ηLa is the apparent viscosity of liquid, ρm is the density of alloy, C is the solidification rate, γ is the shear rate and fs is the fraction of solid. The αand β values depended on chemical composition of alloys and became larger with increasing solute content X. These results were explained by the shape parameter value of suspended particles and the volume fraction of liquid trapped between suspended particles in semi-solid alloys. © 1993, The Iron and Steel Institute of Japan. All rights reserved.