Redetermination of the Fe–Pt phase diagram by using diffusion couple technique combined with key alloys

Fe–Pt intermetallic nanocrystals exhibit good chemical stability and unique magnetic and catalytic properties. However, there are still some discrepancies with regard to the order–disorder transitions of Fe–Pt phases, and experimental works reported for the phase equilibria of Fe–Pt alloys at low temperatures are scarce. Therefore, in this work, the phase equilibria and phase transformations of Fe–Pt alloys were systematically studied by using the diffusion couple technique combined with key alloys through electron probe microanalysis, X-ray diffraction and differential scanning calorimetry. As a result, the composition ranges of the ordered L1₂-Fe₃Pt, L1₀-FePt and L1₂-FePt₃ phases, especially at low temperatures, have been well determined, and the related invariant reactions have been evaluated. Finally, a revised Fe–Pt phase diagram has been proposed.