Thermodynamic analysis of (Ni, Fe)3Al formation by mechanical alloying

(Ni, Fe)3Al intermetallic compound was synthesized by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures of composition Ni50Fe25Al25. Phase transformation and microstructure characteristics of the alloy powders were investigated by X-ray diffraction (XRD). The results show that mechanical alloying resulted in a Ni (Al, Fe) solid solution. By continued milling, this structure transformed to the disordered (Ni, Fe)3Al intermetallic compound. A thermodynamic model developed on the basis of extended theory of Miedema is used to calculate the Gibbs free-energy changes. Final product of MA is a phase having minimal Gibbs free energy compared with other competing phases in Ni–Fe–Al system. However in Ni–Fe–Al system, the most stable phase at all compositions is intermetallic compound (not amorphous phase or solid solution). The results of MA were compared with thermodynamic analysis and revealed the leading role of thermodynamic on the formation of MA product prediction.

► (Ni, Fe)3Al intermetallic compound was synthesized by mechanical alloying.
► We use a thermodynamic analysis to predict the more stable phase.
► We calculate the Gibbs free-energy changes by using extended Miedema model.
► The results of MA compared with thermodynamic analysis and showed a good agreement with it.