Phase diagrams transition metal carbides

The transition metal carbides are some of the highest melting known materials. 5-TaCo.89 melts congruently at 3985 °C and 5-HfCo.94 congruently at 3950 °C. The melting temperatures can be read from the phase diagrams presented in Section 5.2. 

Holleck, H., Ternary Carbide Systems of Actinoids wifli Transition Metals of Other Groups (in German), in Binary and Ternary Transition Metal Carbide and Nitride Systems , Petzow, G. (Ed.) Gebraeder Bomtraeger Berlin, Stuttgart, 92-111 (1984) (Crys. Structure, Phase Diagram, Phase Relations, Review, 91)... 

Line compounds. These are phases where sublattice occupation is restricted by particular combinations of atomic size, electronegativity, etc., and there is a well-defined stoichiometry with respect to the components. Many examples occur in transition metal borides and silicides, III-V compounds and a number of carbides. Although such phases are considered to be stoichiometric in the relevant binary systems, they can have partial or complete solubility of other components with preferential substitution for one of the binary elements. This can be demonstrated for the case of a compound such as the orthorhombic Cr2B-type boride which exists in a number or refractory metal-boride phase diagrams. Mixing then occurs by substitution on the metal sublattice. 

In the systems Co-C and Ni-C and in the other transition metal-carbon systems not mentioned so far, no stable carbide phases are observed. The carbon solnbilities in the metals are of importance for the fabrication and properties of hardmetals (see Section 9.1.1). The phase diagrams are of the entectic type. Metastable carbide phases have been reported in rapidly qnenched Co-C and Ni-C alloys. 

Hoi] Holleck, H., Binary and Ternary Carbides and Nitrides of Transition Metals and Their Phase Relationships (in German), Report KfK 3087B, Kemforschungszentrum, Karlsruhe, 181-183 (1981) (Phase Diagram, Review, 41)... 

The papers presented in the conference span the spectrum of activity in the science of alloys. The theoretical presentations ranged in content from fundamental studies of electronic structure, to first-principles calculations of phase diagrams, to the effects of charge transfer, to the temperature dependence of short-range order parameters. They encompassed the study of mechanical properties, the properties of dislocations, of phase evolution, and computer simulations. Experimental studies were presented based on a variety of state of the art experimental techniques, from TEM to synchrotron diffraction. The phenomena studied varied from the precipitation of nitrides in steel, to the wetting of interfaces between two different crystal structures, to the ordering of vacancies in carbides. And the materials whose properties were measured ranged from Transition metals, to the Lanthanides, to the Actinide series of compounds and alloys. 

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