Treatment of the slurry is important during RheoMetalTM casting. In this work, semi-solid slurries were prepared under different stirring intensities, using two types of stirrers: a naked rod (for regular stirring) and a rod with two blades (for intensive stirring). Tensile tests were performed, investigating fracture surfaces, as well as metallographic samples. The results show that intensive stirring produces castings with finer primary particles and a more homogeneous microstructure. On the other hand, more faceted Fe-rich phases are found along the α-Al grains boundary, due to the dissolution of Fe from the stirrers. Moreover, for intensive stirring castings, the porosity found on the fracture surfaces are smaller, while more second (intermetallic) phases, especially Fe-rich phases, are observed. Consequently, the castings with intensive stirring show worse ductility. Finally, a quantitative analysis was made regarding ductility, affected both by porosity and the presence of Fe-rich phases.