On the Basic Study of the High Energy Product Fe-Pt Permanent Magnet Alloy in the Super-Lattice Type

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The Fept system is known as the super-lattice alloys of CuAuI-type in the face-centered tetragonal, it is the same type as the excellent CoPt magnet alloy. Though, the permanent magnet properties of FePt alloys are extremely inferior to CoPt magnet alloy. The problem of the low coercivity in Fe-Pt system has been left unsolved as a great subject this day. The cause is due to a very high order-disorder transition temperature and a rapid process of ordering, that is a coexistent state of the order-disorder phases not obtained by heat-treatments. We are considered for many experimental data in the past. As the results, the compositions shifted richer in iron than the stoichiometric FePt alloy and the high ordering state disturbed, at the same time, the saturation magnetization increased. Further, the controll of the very difficult heat-treatments turned into a possibility. New Fe-Pt magnets shown the excellent properties of twice the value of the CoPt magnet.Present work, firstly, we have … More been thoroughly investigated for interrelation of the structure in the phase transformation and the several physical properties in Fe-Pt alloys. The origin of the high coercivity is becoming important problem. Especially, we have investigated on the mechanism of the super-lattice type magnet in the Fe-Pt system. Nextly, we have hard worked due to the improvement of the permanent magnet properties. The present work is carried out by means of the magnetic measurement, X-ray diffraction and electron microscopy.The results are summarized as follos: 1. The high coercivity obtained initial phase when transformed from a disorder to order phase. 2. The ultrafine-band-structure observed in the fine twin crystal. 3. The excellent rectangular hysteresis loops remarkably participated in the formation of the twin crystal. 4. The origin of the high coercivity is considered that the pinning of magnetic domains are induced by the interposition of the compositional imperfect order phase and very little residual disorder phase. 5. The improvement of the permanent magnet properties are investigated with the new additional element, which exhibit excellent effect more than the previous Ti, V and Pd, the research is further continued vigorously. Less