Abstract
We have studied the stability of Ni(1−x), -Alx solid solutions at different stoichiometries (x = 0.25 and x = 0.5) via molecular dynamics simulations of models based on an n-body potential. The face-centred-cubic solid solution with x = 0.25 is stable at room temperature against the ordering transformation which occurs at T=360°C via the activation of vacancy diffusion with a release of a disordering enthalpy of 8 kJ(g-atom)−1. The results obtained from the simulated model show an intrinsic instability of the x = 0.5 solid solution which is consistent with experimental results that have revealed the direct formation of NiAl (B2) intermetallic phase accompanied by a considerable heat release.