Thermodynamic re-assessment of the Al–Ir system

Abstract The thermodynamic assessment of the Al–Ir binary system was performed using the CALPHAD technique. The B2-AlIr phase was described, using the two sublattice model with the formula (Al,Ir,V a) 1/2 (Al,Ir,V a) 1/2 , while Al 9 Ir 2 , Al 3 Ir, Al 13 Ir 4 , Al 45 Ir 13 , Al 28 Ir 9 , and Al 2.7 Ir compounds were treated as stoichiometric compounds. The fcc-based phases (L1 0 -AlIr, L1 2 -Al 3 Ir, L1 2 -AlIr 3 and A1) were described using the four sublattice model with the formula, (Al,Ir) 1/4 (Al,Ir) 1/4 (Al,Ir) 1/4 (Al,Ir) 1/4 . From ab initio calculations (VASP) the formation enthalpies of the stable/metastable intermetallic phases involved in the Al–Ir system were estimated. The thermodynamic quantities, such as the phase equilibria, invariant reactions, and formation enthalpies of the intermetallic phases, were calculated using the obtained parameter set, and agree well with experimental data.