Experimental determination of phase equilibria of Al-rich portion in the Al-Fe binary system

Al-rich portion of the Al-Fe binary phase diagram was determined by conventional heat-treatment for equilibration, the diffusion couple method and thermal analysis. Equilibrium compositions are mostly coincident with the generally accepted phase diagram in the literature up to 1000 °C, except the solubility range of θ-Fe4Al13 phase. The solubility ranges of the η-Fe2Al5 and the θ-Fe4Al13 phases were confirmed to increase and incline to the Fe-rich side with increasing temperature. Phase boundaries and the eutectoid composition of the ε-Fe5Al8 phase were determined from the diffusion couple method and heating curves of DSC measurement, which were slightly shifted to a higher Fe concentration. Transformation temperatures of liquidus, solidus and invariant reactions determined from heating curves of DSC measurement were mostly lower than those in the phase diagram evaluated by Kattner and Burton. An invariant reaction related to the formation of the θ-Fe4Al13 phase was confirmed as the peritectic reaction of Liquid + η-Fe2Al5 = θ-Fe4Al13 in this study taking equilibrium compositions of the η-Fe2Al5 + θ-Fe4Al13 phases and solidus temperatures of the θ-Fe4Al13 phase into consideration.