Stabilities of ternary carbides UWC1.75 and UWC2

Abstract

The methane-hydrogen gas equilibration technique has been used to measure the chemical potential of carbon associated with two three-phase fields of the system U-W-C in the temperature range 973 to 1173 K. By combining the values of the chemical potential of carbon in the three-phase fields UC + W + UWC1.75 and UC + UWC1.75 + UWC2 obtained in this study with the data on the Gibbs energy of formation of UC available in the literature, expressions for the Gibbs energies of formation of the two ternary carbides were derived: ΔfGo 〈UWC1.75〉 = -131, 600 - 30.0 T (± 800) J mol-1 ΔfGo 〈UWC2〉 = -144, 800 - 32.0 T (± 10.000) J mol-1 Although estimates of Gibbs energies of formation of the two ternary carbides UWC1.75 and UWC2 have been reported, there have been no previous experimental determinations of thermodynamic properties of these compounds.