1992 Volume 78 Issue 10 Pages 1538-1545
Stirring experiments of Al, Cu and Fe semi-solid alloys on continuous cooling were carried out to investigate the effect of chemical composition and stirring conditions on the apparent viscosity of semi-solid metals.
The apparent viscosity of every alloy increased with increasing solidification rate and decreasing shear rate and the critical fraction solid for fluidity increased with decreasing solidification rate and increasing shear rate. The equation for apparent viscosity ηa of semi-solid alloy is proposed as follows,
ηa=ηLa{1+αρmC1/3γ-4/3/2[1/ƒS-1/(0.72-βC1/3γ-1/3)] }(Pa·s)
α=2.03×102(X/100)1/3
β=19.0(X/100)1/3
where ηLa is the apparent viscosity of liquid, ρm is the density of alloy, C is solidification rate, γ is shear rate and ƒS is fraction solid. The α, 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 trapped liquid volume in suspended particles in semi-solid metals.