Enthalpy of mixing of liquid Al–Cu–Si alloys

Abstract

Abstract The partial and the integral enthalpies of mixing of liquid Al–Cu–Si alloys have been measured by high temperature calorimetry at 1575±3 K. Results for three sections with constant concentration ratios of Al and Si are given in tabular form. A least-square regression analysis of the integral enthalpy of mixing data results in the following relationships (in kJ mol−1; T=1575±3 K): Δ H =x Al x Cu α Al–Cu +x Al x Si α Al–Si +x Cu x Si α Cu–Si +x Al x Cu x Si α Al–Cu–Si α Al–Cu =(−75.6±6.5)+(−63.8±8.8)x Al +(232±33)x 2 Al +(−131±28)x 3 Al α Al–Si =−12.6+2.5x Si α Cu–Si =(−16.2±2.2)+(97.7±37.1)x Cu +(−1138±208)x 2 Cu +(3514±489)x 3 Cu + (−4748±515)x 4 Cu +(2216±199)x 5 Cu α Al–Cu–Si =(−241.7±8.8)+(1165±32)x Al +(891±34)x Si +(−935±30)x 2 Al +(−640±35)x 2 Si + +(−1563±52)x Al x Si . The minimum of ΔH changes with composition from −14.5 kJ mol−1 (Cu–25at.%Si) to −17.3 kJ mol−1 (Al–60at.%Cu). The presence of additional ternary interactions or ternary associates in the liquid state could not be observed.