Abstract:

The concentration of point defects and the relative activity of Al in NiAl alloys at 1273 K were calculated using the Monte Carlo method with the grand canonical ensemble (GCMC). The results were compared to experimental data and theoretical results obtained by the defect correlation model (DCM). When the proportion of Ni atoms is more than 0.475, the lattice model describes the behavior of NiAl alloys well. With a proportion of Ni atoms of less than 0.475 the parameters must be modified because the concentration of vacancies is more than 0.05. The GCMC method simulates the thermodynamic properties of the lattice model well. DCM is an accurate theoretical method but does not describe the thermal excitation of Al vacancies in rich Ni alloys or the correlation of Ni vacancies in rich Al alloys well.

Key words: Intermetallic compound, NiAl alloy, Lattice model, Point defect, Monte Carlo simulation