Soviet Powder Metallurgy and Metal Ceramics

, Volume 4, Issue 2, pp 122–128 | Cite as

The thermodynamic stability of monocarbides of transition metals from sub groups IV – VI

  • R. G. Avatbé
Testing Methods and Properties of Materials
  • 41 Downloads

Summary

  1. 1.

    Chemical bond strength for carbides of transition metals from groups IV–VI increases within each group with increasing atomic number of the transition metal and decreases on transition within the period from a carbide of a group IV metal to a carbide of a group VI metal.

     
  2. 2.

    A weakening of the M-C chemical bond is accompanied by a lowering of the congruent melting temperature for carbides of metals from group IV and a displacement of this temperature into the region of nonstoichiometric compositions for carbides of metals from group V, the least stable carbide-vanadium carbide-melting with decomposition by a peritectic reaction.

     
  3. 3.

    Carbides of transition metals from group IV, as well as tantalum carbide at moderate temperatures, may be regarded as constant-composition compounds, and variable—composition carbide phases based on these carbides-as subtraction solid solutions. A jump of the partial molar characteristics of these stoichiometric carbides gives rise to their congruent vaporization in a wide temperature range.

     
  4. 4.

    Vanadium and niobium monocarbides, as well as tantalum carbide at high temperatures, preferentially lose carbon during vaporization, melt at compositions which are different from stoichiometric, exhibit a continuous change of partial molar characteristics with changing composition, and consequently, may be regarded as variable composition compounds.

     

Keywords

Carbide Vanadium Niobium Carbide Phase Peritectic Reaction 

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Copyright information

© Consultants Bureau Enterprises, Inc. 1965

Authors and Affiliations

  • R. G. Avatbé
    • 1
  1. 1.Order of the Red Banner of Labor State Institute of Applied ChemistryLeningrad

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