SiAlON ceramics are of major interest for industrial applications due to their excellent mechanical properties. The starting Si3N4 powder (α or β), the type of sintering additive and sintering conditions govern the microstructural evolution of SiAlON ceramics. In this study, αı:βı SiAlON ceramics with an equal mole intergranular phase content, different type cation systems (Y:Sm:Ca and Ca:Ce) with different molar ratio (30:64:6 and 33:67) were produced by using coarse (d50=1 µm) β-Si3N4 powder. CaF2 and CaCO3 were utilized as Ca sources. An increase in αı-SiAlON amount in the case of employing CaF2 as opposed to CaCO3 in Y:Sm:Ca cation system was observed. Despite the fact that αı-SiAlON phase cannot be stabilized in Ca:Ce (CaCO3 as a Ca source) system, αı-SiAlON phase stability and unpredictable αı-SiAlON grain-growth in both a and c directions was easily achieved when use of CaF2. Furthermore, using CaF2 instead of CaCO3 gives rise to an increase in densities. Therefore, the impressive effect of CaF2 on abnormal grain growth and αı-SiAlON phase stabilization was discussed.