The crystallization behavior and controlling mechanism of the Si-Fe-C-N system based on polymer-derived SiCN ceramic filled with iron metal powder has been studied. The composite preparation conditions allow the formation of a random distribution of metallic particles in the polymer matrix volume for the Si-C-N system. Pyrolysis of the composite material at 1100 degrees C indicates the presence of one crystalline phase Fe3Si. While the sample pyrolyzed at 1200 degrees C reveals the formation of both Fe3Si and Fe5Si3 phases, a crystallization of beta-SiC is additionally observed by increasing the temperature up to 1300 degrees C. The propensity for the formation of SiC is due to the presence of Fe5Si3, where a solid-liquid-solid (SLS) growth mechanism was suggested to occur. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermal gravimetric analysis with mass spectroscopic detection (TGA-MS) were employed to investigate the crystallization behavior of the Si-Fe-C-N system.