Enthalpy of Formation of Amorphous and Liquid Nickel-Zirconium Alloys

Abstract

Formation enthalpies of amorphous and liquid Zr-Ni alloys were determined by liquid solution calorimetry. Formation enthalpy values of amorphous alloys are presented for the following compositions: Zr 0.75 Ni 0.25 , Zr 0.67 Ni 0.33 , Zr 0.65 Ni 0.35 , Zr 0.60 Ni 0.40 , Zr 0.35 Ni 0.65 , Zr 0.33 Ni 0.67 . Mixing enthalpies of liquid Zr-Ni alloys were measured at 1873K in the concentration range 0-60 at. % zirconium. The formation enthalpies of amorphous and liquid alloys have strong exothermic values. The minimum in formation enthalpies of amorphous and liquid alloys occur at practically the same composition. The experimental values of the amorphous and liquid alloys presented as approximating functions. Application of the ideal association solution model made it possible to derive the formation enthalpies of liquid alloys for the entire concentration range. The experimental data for the formation enthalpies of amorphous and liquid alloys and intermetallic compounds are very close to each other. Based on data for crystallisation enthalpies of amorphous alloys, formation enthalpies of the intermetallic compounds and the mixing enthalpy of liquid alloys, the excess specific heat of the undercooled liquid alloys was estimated. Conclusions about the thermodynamic reasons for easy glass formation in the investigated system were made.