In this work, raw materials analytically pure Al2O3 and analytically pure Fe2O3 were mixed in FeO: Al2O3 molar ratio of 1 : 1and pressed into specimens. The specimens were embedded in analytically pure metal Fe powders and fired slowly to 1650 oCin air atmosphere, and then soaked at 1650 oC for 5 hrs. The fired specimens were investigated by XRD, SEM, and EDS. Theresults show that the specimen synthesized at high temperatures in melting Fe is composed of hercynite and wüstite (FenO(n ≤ 1)); FenO disperses in hercynite; hercynite crystals develop well and are mostly perfect octahedron with grain size around50μm. The hercynite has Fe/Al ratio smaller than 1/2, which is non-stoichimetric. With the existence of melting Fe, althoughthe raw materials are theoretically batched according to FeO·Al2O3, FenO is still excess, so the hercynite obtained is Al-rich.

Keywords: Melting Fe surrounding, Hercynite, Wüstite, Non-stoichiometric