A thermodynamic analysis of the NiAl system

Abstract

Abstract Phase equilibrium and thermodynamic data of the binary NiAl system are analyzed using thermodynamic models. The liquid and fcc (γ) phases are treated as disordered solutions, the intermetallic compounds with appreciable ranges of homogeneity, i.e. γ′-(Ni3Al), B2-(NiAl) and Al3Ni2, are described by compound energy models, and the other intermetallic phases are taken to be line compounds. The phase equilibrium and thermodynamic properties calculated from the model parameters are in accord with most of the experimental data reported in the literature. For γ′-(Ni3Al) and B2-(NiAl), the model-calculated defect concentrations as functions of temperature and composition are in agreement with experimental data. In comparison to previous thermodynamic descriptions reported in the literature, the present one has fewer model parameters with more reasonable values. Despite this, the agreement between model-calculated thermodynamic values and phase boundaries and experimental data is as good as or better than that obtained in earlier studies.