Enthalpy of formation of quasicrystalline phase and ternary solid solutions in the Al-Fe-Cu system

Abstract

Standard enthalpies of formation of quasicrystalline phase and the ternary solid solutions in the Al-Fe-Cu system and the intermetallic compound FeAl were determined by the means of solution calorimetry. The quasicrystalline phase was prepared using two different methods. The first method (I) consisted of ball milling the mixture of powders of pure aluminum copper and iron in a planetary mill with subsequent compacting by hot pressing and annealing. The second method (II) consisted of arc melting of the components in argon atmosphere followed by annealing. The latter method was used for preparing the compound FeAl and the solid solutions. The phases were identified using the XRD method. The enthalpy of the formation was determined for the quasicrystalline phase of the composition Al 62Cu 25.5Fe 12.5 and the ternary BCC solid solutions Al 35Cu 14Fe 51, Al 40Cu 17Fe 43, and Al 50.4Cu 19.6Fe 30. The measured enthalpy of formation of the intermetallic compound FeAl is in good agreement with the earlier published data. The enthalpies of formation of the quasicrystalline phases prepared using two different methods are close to each other, namely, −22.7±3.4 (method I) and −21.3±2.1 (method II) kJ/mol.