2935.     RUFF, O., JELLINEK, E., AND FOEHR, T.  [Constitution and Thermal Stability of Carbides.]  Ztschr. Elektrochem., vol. 24, 1918, pp. 157-162; Chem. Abs., vol. 13, 1919, p. 213.

        Experiments on the formation of carbides lead to the conclusion that metal carbides in general are stable up to temperatures above 2,500, and even at these elevated temperatures, C does not dissolve in the metals as such, but as a carbide of the metals.  To date, the known metal carbides conform with the following hydrocarbons:  CH4, C2H6, C2H2, C2H4, and C4H10.  In the case of most metals the C concentration increases with increasing temperature.  Within wide temperature limits carbide such as Mn3C, Cr5C3, and W3C are very stable; carbides such as Fe3C, WC, and Cr3C2 decompose upon lowering the temperature to the melting point of the alloy into metal plus C.  Fe3C is difficult to obtain in the solid phase, and Ni3C is altogether unstable as solid.  All carbides dissociate more or less completely upon volatilization.