Thermodynamic evaluation of the Mo-rich corner of the Mo-Hf-C system including O impurities

In this paper the phase fractions of (Hf,Mo)C and (Mo,Hf)2C carbide phases are investigated experimentally in the low Hf and C alloyed composition range of technological Mo-Hf-C applications. Furthermore, solubilities of Hf and C in body centered cubic Mo-base solid solution (Mo-bcc) are evaluated with consideration of the presence of O-impurities. The results, together with thermodynamic stability data from first-principles analysis, are taken into account in thermodynamic model descriptions of the solid alloy and carbide phases. The presented modeling considers O solubility in Mo-bcc and (Hf,Mo)C, as well as the role of O impurities in MHC, a Mo-Hf-C alloy with a nominal composition of 0.65 at.% Hf and 0.65 at.% C, is discussed. Finally, a typical application of the optimized thermodynamic database for the prediction of phase stabilities in MHC is presented. © 2016 Elsevier B.V.