Abstract:In the present work,the as-cast solidified microstructures of the Ce-Ge alloys between 40-60 at.% Ge are measured by XRD, SEM and EPMA in order to verify some of the invariant reactions of the Ce-Ge system. The experiments show that the compound (CeGe) melts congruently; the compound Ce5Ge4 is formed by the invariant peritectic reaction L+Ce5Ge3→Ce5Ge4 and the microstructures of two eutectic reactions L→Ce5Ge4+(CeGe) and L→(CeGe)+(βCeGe1.7) are observed. According to the present investigation, some phase equilibrium relations of the Ce-Ge phase diagram reported in the literature are modified.