Hydrogen Induced Disproportionation of Zr2Ni : Temperature Dependence

The kinetics of hydrogen induced-disproportionation of Zr2Ni was measured in a hydrogen atmosphere in a temperature range from 723 to 898 K. The disproportionation process of Zr2Ni was found as Zr2Ni + H2 -> ZrH2 + ZrNi. This reaction was completed within 100 s at all temperatures. The Avrami-Erofeev equation was used to analyze the reaction mechanism. It was found that the mechanism could be described by a nucleation and nuclei growth model. The activation energy for the disproportionation was determined to be -3 kJ/mol, which is slightly larger than that of Zr2Co (-15 kJ/mol). The negative temperature dependence was examined by the decrease in the number of product nuclei, owing to the reduction of hydrogen solubility in the reactant phase, with increase in temperature