High coercivity FePt–C bulk magnet processed by spark plasma sintering and hot deformation

A high coercivity of 11 kOe has been obtained in spark plasma sintered and hot-deformed Fe53Pt44C3 bulk magnets. The origin for the high coercivity has been investigated using X-ray diffraction and transmission electron microscopy. The average grain size of the ordered phase was ∼100 nm, which is less than the single domain size of the L10-FePt phase. Fe3C particles were found surrounding the L10-FePt grains, which suppress the grain growth. The L10 ordering is also found to increase in hot-deformed sample by annealing in a magnetic field of 10 T at 600 °C.