Hard magnetic materials: rare earth-transition metal and Fe-Nd-B

This chapter discusses on magnetic materials. Room temperature intrinsic properties, crystal anisotropy constant, magnetic saturation, anisotropy field, coercive field, magnetic remanence and Curie temperature of Co-RE, Fe-Nd-B based permanent magnet are summarized. Powder metallurgical (PM) processing of Co-Sm and Fe-Nd-B based permanent magnet is also discussed. Physical properties of sintered Co-Sm magnet are given. Range of chemical composition of high energy magnets is given. High energy TM₁₇Sm₂ magnets for applications up to 300°C, typical values of commercially available magnets which may be used without coatings are demonstrated. Chemical composition of commercial 17/2 magnets, applicable for operating temperatures up to 550°C is demonstrated. Physical properties of sintered TM₁₇Sm₂ magnets are given. The temperature dependence of the intrinsic coercivity for Co-Sm magnet can be varied widely by modifications of the concentration of the substitutional elements and of Sm. Demagnetization curves of commercially available magnets are illustrated. Influence of substitution elements of Fe-Nd-B type magnet is illustrated. Magnets made by rapid quenching/hot working technique are also described. Change of remanence and coercivity of dense magnets, manufactured by the hot pressing - hot deforming technique is also illustrated in this chapter.