https://cimav.repositorioinstitucional.mx/jspui/ 1 Nanocrystalline PrCo 5 alloy obtained by mechanical milling F. J. Rivera-Gómez, J.T. Elizalde-Galindo, J.A. Matutes-Aquino Abstract Nanostructured PrCo5 powderswere obtained by mechanical milling, annealing in high vacuum in sealed ampoules and subsequent quenching in water. The highest intrinsic coercivity value (iHC = 1.385MA/m) and magnetization ratio (σr/σmax = 0.66) were determined in powders milled for 240 min and annealed at 1073K for 1 min. The enhanced remanence (σr/σmax > 0.5) suggests strong exchange interactions between the adjacent crystallites. This is in good agreement with the small average crystallite size, <D> = 15 nm. The high magnetic properties observed in these nanostructured PrCo5 intermetallic alloys have their origin in its relatively high uniaxial magnetocrystalline anisotropy field, and in the homogeneous nanostructure developed by mechanical milling process and subsequent annealing. Keywords: Permanent magnets, Nanostructured materials, Rare earth alloys and compounds, Microstructure. Introduction Permanent magnets are fabricated with magnetic materials that show strong resistance to invert its magnetization, they maintain the magnetization large and stable when subjected to their own demagnetizing fields, and to opposing external fields, and to a range of temperature changes. The properties that define this behavior are intrinsic coercivity, iHc, and remanent magnetization, σr. They determine the maximum energy