In-situ microstructure observation and rheological measurement of SCN-5at.%WATER alloy in the semi-solid state

A novel apparatus for in-situ microstructure observation with synchronous rheological measurement was developed. Using this apparatus, the relationships between microstructure evolution and rheological properties of a semi-solid SCN-5%Water model alloy under different shearing conditions were systematically investigated. Experimental results show that under the continuous cooling with shearing, spherical particles have little influence on the slurry viscosity at low solid fractions. Whereas, when the solid fraction exceeds a threshold, the apparent viscosity increases rapidly. Especially, it should be indicated that at a given fraction solid and shearing condition, the degree of agglomeration of solid particles has a remarkable effect on the measured viscosity. Based on these, a rheological model has been developed, which takes into account the effects of temperature, shear rate, particle radius, and the degree of agglomeration, which shows a good agreement with the experimental results.