Thermodynamic properties of liquid, undercooled liquid and amorphous Al-Cu-La-Ni alloys

The integral enthalpy of mixing of liquid Al-Cu-La-Ni alloys for vertical sections with x(Al):x(Ca):x(Ni)=0.16:0.68:0.16 and x(Cu):x(La):x(Ni) = 0.13:0.74:0.13 was determined by solution calorimetry at 1173 and 1081 K, respectively. An adiabatic calorimeter was used to measure the heat capacity C-p(1) of liquid Al25Cu10La55Ni10. The heat capacity of undercooled Liquid; amorphous and crystalline Al25Cu20La55 and AI,,Cu,,La,,Ni,, alloys was measured by differential scanning calorimetry (DSC). The association model was applied to calculate the thermodynamic properties of Liquid and undercooled liquid Al-Cu-La-Ni alloys using the model parameters of the six limiting binary and four limiting ternary alloys. The measured C-p(1)(T) of liquid Al25Cu10La55Ni10 at the liquidus temperature is larger than that of the undercooled liquid state above the glass transition temperature. The calculated C-p(1)(T) curve exhibits a maximum for undercooled liquid Al25Cu10La55Ni10. (C) 1999 Elsevier Science S.A. All rights reserved.