Re-examination of Phase Diagram of Fe-Pt System

抄録

The phase boundaries pertaining to γ₂ (FePt) and γ₃ (FePt₃) phases in the Fe-Pt system have been re-examined by measuring (1) the compositions of interphase boundaries in diffusion couples, (2) the equilibrium compositions in two-phase alloys and (3) the electrical resistivity as a function of temperature. The results obtained by the three methods are consistent with each other. The γ (fcc solid solution) ↔ γ₂+γ₃ eutectoid has been found to be located at a point higher in Pt concentration and lower in temperature than in the currently adopted phase diagram, the stability range of the γ₂ phase exhibits considerable asymmetry. Other phase boundaries, as well as the ferromagnetic ↔ paramagnetic transition in the γ₂ phase detected by the resistivity measurements, are in fair agreement with the data in the literature.