Influence of Nd/Nd2Fe14B interface microstructure on the coercivity of surface Nd2Fe14B grains in Nd-sputtered Nd–Fe–B sintered magnets

The influence of local microstructures on the coercivity of a sintered Nd–Fe–B magnet has been investigated using a combination of magnetic measurements and cross-sectional transmission electron microscopic studies of the interfaces between surface grains of thin Nd–Fe–B magnets and sputter-deposited Nd films on the surface. The TEM study suggested that formation of an Nd oxide phase with a metastable face-centered cubic structure on the surface Nd2Fe14B grains is strongly related to the onset of coercivity in the Nd–Fe–B magnets.