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Partial and integral enthalpies of mixing of liquid Ag–Al–Cu and Ag–Cu–Zn alloys
Ist Teil von
Journal of alloys and compounds, 2002-05, Vol.337 (1-2), p.189-201
Ort / Verlag
Lausanne: Elsevier B.V
Erscheinungsjahr
2002
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
The partial enthalpies of mixing of the components of liquid ternary Ag–Al–Cu (T=1252±5 K) and Ag–Cu–Zn (T=1068–1113 K) alloys have been determined using a high-temperature isoperibolic calorimeter. Measurements were performed starting from both pure Al and Zn and from binary liquid Ag–Cu alloys along sections with constant Ag:Cu ratios 1:3, 1:1, 3:1 (Ag–Al–Cu system) and 2:3, 3:2 (Ag–Cu–Zn system). The integral enthalpies of mixing of these ternary alloys are calculated from the partial enthalpies of mixing using different methods. The composition dependences of the partial and integral enthalpies were simultaneously analytically described according to a Redlich–Kister–Mugianu equation using a least-squares fit by Gauss–Newton method. In case of Ag–Al–Cu alloys square- and higher order terms in excess ternary part are needed to adequately describe the surfaces of enthalpies of mixing. Enthalpy data for the constituent binaries were adopted from latest calorimetric measurements and thermodynamic assessments of the phase diagrams. The evaluated integral enthalpy of mixing demonstrates that the minima for the Ag–Al–Cu (−17.1 kJ mol−1) and Ag–Cu–Zn (−10.0 kJ mol−1) correspond to binary compositions Al0.40Cu0.60 and Cu0.50Zn0.50, respectively.