Bulk nanocomposite LaCo5/LaCo13 magnets

The effects of processing parameters and composition on the magnetic properties and microstructure of nanocrystalline La-Co based hard magnetic materials were investigated. Bulk nanocomposite LaCo5/LaCo13 magnets were fabricated by mechanical alloying of LaCo5 and La2Co7 powder mixtures and subsequent hot pressing at 580-810 degrees C. A high coercive field (H-c) of over 16 kOe with a smooth demagnetization curve was obtained in a composition range of 25-30 wt. % La2Co7 when hot-pressed at 660-760 degrees C. Microstructural investigations indicated that the magnets consist of a primary LaCo5 phase with grain sizes of 200-400 nm, coexisting with 20-100 nm grains of LaCo13 located both at the grain boundaries and within the hard LaCo5 grains. (C) 2011 American Institute of Physics. [doi:10.1063/1.3562446]