Experimental determination of the formation enthalpies of zirconium-nickel-aluminium amorphous alloys

Abstract

A method of solution calorimetry has been applied for thermochemical study of amorphous alloys in the Zr-Ni-Al system. Heats of dissolution for five amorphous alloys Zr 0.60Ni 0.40, Zr 0.60Ni 0.35Al 0.05, Zr 0.60Ni 0.30Al 0.10, Zr 0.60Ni 0.25Al 0.15 and Zr 0.60Ni 0.20Al 0.20 in liquid Al were measured with the help of high temperature isoperibol Calvet-type calorimeter. The measured molar heats of dissolution along with these values for pure nickel and zirconium determined before allowed to calculate molar enthalpies of formation for the listed amorphous alloys from the pure constituent metals in the crystalline state. Enthalpy of formation for the Zr 0.60Ni 0.40 amorphous alloy is in good agreement with both our previous results for the amorphous alloys in the Zr-Ni system and the available literature data. Enthalpies of formation for the Zr-Ni-Al amorphous alloys from the pure crystalline metals are strongly negative that shows considerable negative deviation of these alloys from the ideal behaviour and points to considerable interaction energy between atoms of these components in amorphous phase. Partial substitution Ni by Al in the Zr 0.60Ni 0.40 amorphous alloy results in an increase of enthalpy of formation at low concentration of Al followed by a decrease of this value at higher concentration of Al, i.e. small addition of Al into Ni-Zr based amorphous alloy decreases and considerable addition of Al increases bond forces in this phase.