Enthalpy of mixing of liquid Cu–Fe–Hf alloys at 1 873 K

Abstract

Abstract In the ternary Cu–Fe–Hf system, the mixing enthalpies of liquid alloys were investigated at 1873 K using a high-temperature isoperibolic calorimeter. The experiments were performed along the sections x Cu/x Fe = 3/1, 1/1 at x Hf = 0–0.47 and along the section x Cu/x Fe = 1/3 at x Hf = 0–0.13. The limiting partial enthalpies of mixing of undercooled liquid hafnium in liquid Cu–Fe alloys, Δ mix H ¯ Hf ∞ ${\Delta _{{\rm{mix}}}}\bar H_{{\rm{Hf}}}^\infty $ , are (−122 ± 9) kJ mol−1 (section x Cu/x Fe = 3/1), (−106 ± 9) kJ mol−1 (section x Cu/x Fe = 1/1), and (−105 ± 2) kJ mol−1 (section x Cu/x Fe = 1/3). In the investigated composition range, the integral mixing enthalpies are sign-changing. For the integral mixing enthalpy, an analytical expression was obtained by the least squares fit of the experimental results using the Redlich–Kister–Muggianu polynomial.