Corrosion of highly coercive, highly textured Nd-Fe-B films

The stability and corrosion of highly coercive and highly textured Nd-Fe-B films is examined. The rapid degradation of coercivity within hours after deposition and the relatively slow reduction of remanence and magnetic texture together with depth profile analysis show that oxidation of the Nd-rich intergranular phase is the first step of corrosion. Consequences on coercivity are discussed together with a reduction of the local anisotropy field at the surface. For applications of thin Nd-FeB films degradation can be inhibited by covering with a Cr protection layer.