Three types of semi-solid slurry (35, 45, and 55%) are fabricated through solidification of A356 alloy using electromagnetic stirring at or above the liquidus temperature, and also through solidification in air without stirring. Thin plates are then fabricated by inserting the semi-solid slurries into an indirect closed die and applying compression. For the stirred semi-solid slurries, a globular structure is found to be dominant, while a dendrite structure is dominant in the unstirred semi-solid slurriesspecimens. Solid spheroid particles are generated, not because of dendrite arm separation, but because the irregularly shaped nuclei created through the dendrite structures are expelled from these structures under the influence of an intense liquid fluid flow. During movement, the particle boundaries are plastically deformed, and the particles develop spheroid shapes in response to wear due to collision with other particles. When the particles are not influenced by stirring or any other factor, the nuclei develop into increasingly irregular particles. As solidification progresses, diffusion causes the particles to move close together to form a bonded dendrite structure. Under a large strain rate, and if the stirred semi-solid slurry is compressed, solid particle groups that were previously bonded through diffusion become separated into individual particles once more, as the bonds are broken. The solid particles and residual liquid phase move in a turbulent flow state, because the flow velocity is accelerated significantly as they pass through gates with narrow cross-sections. Because of the frictional forces generated during motion and the wear caused by collisions between the particles, the particle sizes are reduced and the curvature of the corners is increased, leading to increased deformation to spheroid particle shapes.