RETM5 and RE2TM17 permanent magnets development

RETM5 and RE2TM17 (RE = rare earth, TM = transition metal) permanent magnets are discussed. The scientific and technological considerations which have guided their development are described to help establish the framework within which most of the work can be integrated and understood. The review limits itself to the technologically significant SmCo5 material and to those processes which have been demonstrated as capable of producing magnets in bulk useful form. Areas covered include phase diagrams, crystal structures, magnetocrystalline anisotropy, coercivity mechanisms, fabrication technologies, processing-microstructure-property interrelationships, and thermal effects related to stability of magnet flux.