Corrosion behavior of Nd–Fe–B/α–Fe nanocomposite magnets

Abstract

For the fundamental evaluation of corrosion properties of nanocrystalline Nd–Fe–B-based magnets, different phase mixtures with compositions varying from single phase Nd 2Fe 14B to Nd 2Fe 14B+10 wt% Fe, Nd 2Fe 14B+25 wt% Fe and Nd 2Fe 14B+35 wt% Fe were prepared via intensive ball milling and subsequent hot-pressing. Before and after corrosion measurements, the samples were investigated by means of high-resolution scanning electron microscopy. Potentiodynamic polarisation measurements were performed in 0.5 M phthalate buffer ( pH = 5 ). With increasing α–Fe fraction, a decrease of the corrosion rate is observed as well as improved passivation.