Massive transformation in FeNi nanopowders with nanotwin-assisted nitridation.

L1-ordered FeNi alloy (tetrataenite), a promising candidate for rare-earth-free and low-cost permanent magnet applications, is attracting increasing attention from academic and industrial communities. Highly ordered single-phase L1-FeNi is difficult to synthesis efficiently because of its low chemical order-disorder transition temperature (200-320 °C). A non-equilibrium synthetic route utilizing a nitrogen topotactic reaction has been considered a valid approach, although the phase transformation mechanism is currently unknown.

Novel powder processing technologies for production of rare-earth permanent magnets.

Post-neodymium magnets that possess high heat resistance, coercivity, and are desired for future-generation motors. However, the candidate materials for post-neodymium magnets such as SmFeN and metastable magnetic alloys have certain process-related problems: low sinterability due to thermal decomposition at elevated temperatures, deterioration of coercivity during sintering, and the poor coercivity of the raw powder. Various developments in powder processing are underway with the aim of overcoming these problems.