2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 6: Coatings, Cement, Rare Earth & Ferro-alloys

Editors:Kongoli F, Yildirim H, Hainer S, Hofmann K, Proske T, Graubner C.A., Albert B
Publisher:Flogen Star OUTREACH
Publication Year:2015
Pages:200 pages
ISSN:2291-1227 (Metals and Materials Processing in a Clean Environment Series)
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    Phase Diagrams with Allotropies and System Fe-Co-S

    Vasily Lutsyk1; Vera Vorob'eva1; Edward Nasrulin1; Olga Sumkina1;
    Type of Paper: Regular
    Id Paper: 115
    Topic: 12


    The study of the sulfide system Fe-S-Co was limited by the quasi-binary section through the compositions of congruently melting sulfides FeS and CoS. The fields of all three polymorphous modifications of iron are located on the T-x-y diagram liquidus of the subsystem Fe-FeS-CoS-Co: high-temperature delta-Fe, intermediate gamma-Fe and low-temperature alpha-Fe. Besides them, on the diagram there are fields of the liquidus of the incongruently melting compound Co4S3 and the solid solution formed by the compounds FeS and CoS. A transition from the high-temperature polymorphous modification of iron to the intermediate one occurs according to the univariant metatectic reaction L+delta-Fe=gamma-Fe(Co), and from the intermediate modification to the low-temperature one according to the invariant reactions in the presence of the solid solution FeS(CoS) or the compound Co4S3: L+gamma-Fe(Co)=alpha-Fe(Co)+FeS(CoS) and L+gamma-Fe(Co)=alpha-Fe(Co)+Co4S3. Furthermore, the ternary eutectic invariant reaction takes place: L=alpha-Fe(Co)+FeS(CoS)+Co4S3. As a result, the T-x-y diagram consists of 69 surfaces and 28 phase regions. The T-x-y diagram 3-dimensional (3D) computer model is designed into several stages. First, the prototype is formed. It consists of the ruled surfaces, which are the boundaries of the 3-phase regions: 8 with the liquid L and 3 without it. Three horizontal (isothermal) planes are formed automatically above and lower. These are the complexes, each of which consists of 4 simplexes and corresponds to one of 3 invariant reactions. Then, 5 surfaces of liquidus, 5 solidus, 10 solvus, two pairs of the surfaces of transus, between which are located two regions of the coexistence of iron in two versions of the allotropy: delta- Fe and gamma-Fe, gamma-Fe and alpha-Fe, are constructed. 3D computer model of the real system is obtained after correction according to the experimental data of the curvature of lines and surfaces. It makes it possible to construct any isothermal section and isopleth and to demonstrate the results of the mass balances calculations, so that it is possible to see, as the phase and conglomerate concentration of the heterogeneous mixture changes with a temperature decrease.
    The work was partially supported by the Russian Foundation for Basic Research (projects 14-08-00453 and 14-08-31468).


    Ferro-Alloys; Metallurgy; Metals; Technology;

    Cite this article as:

    Lutsyk V, Vorob'eva V, Nasrulin E, Sumkina O. Phase Diagrams with Allotropies and System Fe-Co-S. In: Kongoli F, Yildirim H, Hainer S, Hofmann K, Proske T, Graubner C.A., Albert B, editors. Sustainable Industrial Processing Summit SIPS 2015 Volume 6: Coatings, Cement, Rare Earth & Ferro-alloys. Volume 6. Montreal(Canada): FLOGEN Star Outreach. 2015. p. 123-124.