Analysis of SmCo 2:17 sintered magnets by electron diffraction (abstract)

摘要

Precipitation‐hardened SmCo 2:17 sintered magnets contain a multiphase, cellular microstructure,1which is determined by nominal composition and heat treatment parameters. A correlation between microstructure and coercivity has been shown by transmission electron microscopy (TEM).1,2Magnets with different samarium content were investigated. In magnets withiHc<700 kA/m a high density of basal stacking faults (microtwinning) within the hard magnetic, rhombohedral 2:17 phase was shown. Local changes of crystal lattice parameters are observed in low coercivity magnets. Calculated diffraction patterns of CaCu5‐, TbCu7‐, Th2Zn17‐, and Th2Ni17‐crystal structures with different types of atomic occupancies3are compared with experimental electron diffraction patterns obtained by TEM. Our study revealed that the local composition within the hard magnetic grains influences the precipitation structure which is necessary for achieving magnetic hardness by domain wall pinning.