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.