2511.     ---------------.  [ÖHMAN, E.]  [Carbides in the Iron-Manganese-Carbon System.]  Jernkontorets Ann., vol. 128, 1944, pp. 13-16; Chem. Abs., vol. 39, 1945, p. 3198.

        X-ray study made in 1926 of the carbides present in the above system revealed a hitherto unknown double carbide of Mn and Fe, which has a monoclinic crystal structure.  By solution of C in molten Mn, carbides are produced, which, according to X-ray powder photographs, are isomorphous with the Cr carbides Cr₂₃C₆ and Cr₇C₃.  As the powder photographs are in exact agreement with those obtained for the above Cr carbides, the Mn carbides probably have the formula Mn₂₃C₆ and Mn₇C₃.  The latter has been observed only in alloys with more than 80% Mn, whereas Mn₂₃C₆ is found with up to 50% Fe and less than 6% C present.  With more than 50% Fe cementite is the only carbide formed.  Both cementite and Mn₂₃C₆ are present even when the Mn content is up to 70%, Mn can replace Fe in cementite to a considerable extent.