Enthalpy of formation of UZr2 by calorimetry

The enthalpy of formation of the intermetallic compound UZr2 at 298 K was determined by high temperature solution calorimetry in which liquid aluminium was used as the solvent. The thermal effects of dissolution of U, Zr and UZr2 in liquid aluminium were measured in separate experiments by dropping the samples held at ambient temperature into liquid aluminium maintained at 991 K in the calorimeter. The thermal effects of dissolution of the samples in liquid aluminium at infinite dilution were derived from these measurements, and based on these data the enthalpy of formation of UZr2 at 298 K was computed as -4.0 kJ mol-1. The partial enthalpy of solution of zirconium in liquid aluminium at infinite dilution was also computed and the value thus obtained was -(257.7±9.5) kJ mol-1. (orig.)