Abstract
The susceptibility of Nd-Fe-B permanent magnets to oxidation and/or corrosion makes problems not only during manufacturing, but also influences reliability and durability of components containing such permanent magnets. In this work, corrosion processes of Nd-Fe-B PMs were studied on the samples taken from rotors of servomotors operating approximately the same time at similar conditions. Two mechanisms of degradation in usual environmental conditions were found - oxidation of intergranular Nd-rich phase caused mechanical disintegration of sintered magnet body to individual grains of hard magnetic Nd₂Fe₁₄B phase and subsequent oxidation of these grains. The first step is of great importance. It was found that not only oxidation of the intergranular thin layer of Nd-rich phase contributes to the destruction of magnet, but also internal stresses arising from difference in specific volume of this phase and oxides.

Key words
neodymium permanent magnets, corrosion

Full text not available