Thermodynamic modelling of multicomponent cubic Nb, Ti and V carbides/carbonitrides

Thermodynamic descriptions of multicomponent carbides and carbonitrides with Nb, Ti and V, evaluated using experimental information from the literature, are presented. The descriptions are validated by calculating solubilities of the carbides and carbonitrides in cemented carbides and steel, and comparing them with experimental information. The agreement is good, and it is shown that the agreement is significantly better using the new descriptions of the carbides and carbonitrides, than using previously available descriptions. To obtain this result, miscibility gaps in a number of three, four- and five-component systems were evaluated, and the calculated miscibility gaps are presented. Reliable calculations of the dependence of the nitrogen content in a C-Co-Ti-W cemented carbide on the nitrogen activity of the sintering gas, are presented. The calculated predictions of the solubilities of Ti, V, Nb-V, Ti-Nb, and Ti-V carbonitrides in steel, in close agreement with experimental information, are shown.