Abstract

Samples of Sm2Co17-type magnets with difier­ent coercivity and quenching rate were studied by transmission electron microscopy. The microstructure of Sm2Co17-type magnets is described. The high coer­civily samples showed a well developed cellular microstructure with thick Sm(Co,Cu)5 walls. The hex­agonal platelet phase runs as long straight lines crossing the cell walls. The low coercívity sample showed a chaotic precipitación of the Sm(Co.Cu)5 phase while the hexagonal platelet phase is more densely packed and runs as short straight lines in the TEM micrographs. Quantitative measurement of platelet density and cell size were made and correlated with the coercive field value