Nano-structured YCo_{5 alloy with enhanced hard magnetic properties

Enhanced hard magnetic properties were obtained by the mechanical milling of cast Y1.07Co5 alloy and subsequently annealing the powder. The best magnetic properties have been obtained in powders milled for four hours, annealed in high vacuum at 830°C for 2.5 minutes and quenched in water, with a coercivity of 10.2 kOe, and a high σr/σmax ratio of 0.69. Microstructure studies show that the annealed powders have a nearly single phase YCo5 structure with an average grain size of 20 nm. The enhanced hard magnetic properties are attributed to the high anisotropy field of the YCo5 phase and to the magnetic exchange interactions associated with the nanoscale grain size.