Fe-S-Ta (Iron-Sulfur-Tantalum)

摘要

The previous review of this system by [1988Rag] presented a tentative partial isothermal section at 900 deg C for Fe-rich alloys. Recently, [2004Wad] determined an isothermal section for this system at 950 deg C, which depicts three ternary compounds.Binary SystemsThe Fe-S phase diagram [1982Kub] depicts two intermediate phases. The monosulfide Fe_1-xS (NiAs-type hexagonal) is stable at Fe-deficient (S-rich) compositions and has a range of 50-55 at.percent S. Cubic FeS_2 (pyrite) forms peritectically at 743 deg C and undergoes a transition to the orthorhombic form (marcasite) at 425 deg C. The Fe-Ta phase diagram [1993Swa] has two intermediate phases: Fe_2Ta (C14, MgZn_2-type hexagonal) and FeTa (mux) (D8_5, Fe_7W_6-type rhombohedral). The S-Ta phase diagram is not known. The intermediate phases, TaS_2 Ta_1+x.S_2, Ta_3S_2, and Ta_6S, are shown as stable at 950 deg C by [2004Wad].