現象論的計算によるFe-Pt2元系FePt_3及びFePt規則相平衡状態図の評価

概要

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A phenomenological calculation based on the cluster variation method combined with a Lennard-Jones type pair-wise atomic interaction energies has been attempted for an Fe-Pt binary system. The phase equilibria for FePt_3-disorder and FePt-disorder are investigated. In particular, a tetragonal distortion is explicitly considered for the FePt L1_0 ordered phase. The derived Lennard-Jones type potentials imply that the Fe-Pt system has an ordering tendency. The calculated FePt_3-disorder and FePt-disorder phase boundaries well reproduce tendencies of the experimental ones, and the FePt L1_0 ordered phase is more stabilized by taking a tetragonal distortion into account. The order-disorder transition temperatures are, however, underestimated about 580K, and the calculated tetragonality for the FePt L1_0 ordered phase at 1 : 1 stoichiometry is slightly different from the experimental value. These discrepancies are considered to be mainly caused by the underestimation of the employed heats of formation for the FePt_3 L1_2 ordered phase. The results of the present study are applicable to further investigation of the stability for the FePt L1_0 ordered phase.
北海道工業大学の論文
2007-03-26