Effect of the Shape of Solid Particles on the Distribution of Particles in JIS AC4CH (A356) Aluminum Alloy Semi-Solid High-Pressure Die Casting

In the semi-solid high-pressure die casting process, the slurry flows as a solid liquid two-phase flow. In this study, the effect of the shape of solid particles on their distribution in the slurry was investigated. The solid particles were concentrated in the center of the flow direction in the case of globular-shaped solid particles and high-flow-velocity conditions. Moreover, the concentration ratio of the solid particles increased with an increasing Reynolds number. This phenomenon was explained as follows. The shape of the solid particles affected the viscosity of the slurry; the viscosity was decreased by the globular particles. The solid panicles applied Saffman force, which is generated by the velocity gradient, and moved in the direction away from the solid liquid interface. The Reynolds number increased with decreasing viscosity or increasing flow velocity; therefore, the Saffman force increased with an increasing Reynolds number.