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Fe/Si3N4 composite powder was synthesized by the heterogeneous precipitation-thermal reduction process, and then pressed into flakes under a pressure of 10 MPa. Flakes were sintered by pressureless and hot-pressing at 1 600 °C under 0.1 MPa N2. The chemical composition, phases and microstructure of composite powder and sintered flakes were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the structure of composite powders is Si3N4 coated by nano Fe. The crystal phases of sintered flakes by pressureless are Fe(Si) compound, SiC and Si3N4. The crystal phases of the sintered samples by hot-pressing are Fe, Fe(Si) compound and Si3N4. It is found that crystal phases flakes obtained by pressureless and hot-pressing are very different. [ABSTRACT FROM AUTHOR]