Influence of Time Evolution of Particle Shape on Rheological Behavior of Semisolid Slurries of Magnesium Alloy AZ91D

摘要

To gain the insights into the influence of the morphology of solid particles on rheological behavior of semisolid metal slurries, the time evolution of Hausdorff dimensionality describing the particle morphology is deduced in order to quantitatively analyze the time evolution of the particle morphology. In consideration of the role of the liquid entrapped by non-spherical solid particles, the non-spherical solid particles with the entrapped liquid are treated as spherical solid particles, and the equivalent solid volume fraction is defined as the sum of solid volume fraction and the volume fraction of the entrapped liquid. This model could be used to analyze the rheological behavior of the semisolid metal slurries containing the non-spherical particles with Hausdorff dimensionality less than 3. Moreover, the rheological behavior of semisolid magnesium alloy AZ91D is theoretically analyzed by this model during isothermal shearing and continuous cooling. The calculated results are found coinciding with the experimental results and the calculated results also reveal that the shear rate and cooling rate could influence the rheological behavior of semisolid metal slurries by changing the morphology of solid particles except by affecting agglomeration degree.