The effect of absorbed hydrogen on the corrosion behavior of sintered NdFeB magnet

The absorption of hydrogen by NdFeB magnet has been investigated by using the electrochemical charging technique at constant cathodic current density I_c ranging from 0 to 4 mA/cm². Open circuit potential measurements (OCP) and polarization curves were carried out to study the corrosion behavior of the charged NdFeB magnet in 0.01 mol/L NaCl solution. The results showed that hydrogen had a strong influence on the corrosion of NdFeB magnet. The open circuit potential became gradually negative due to the hydrogen incorporation into the NdFeB magnet. The corrosion resistance was reduced gradually with the increasing cathodic current density I_c. The surface structure and the morphology of the charged NdFeB magnet were examined by XRD and SEM. The results revealed that the effect of the absorbed hydrogen focused mostly on accelerating the exfoliation corrosion of Nd₂Fe₁₄B matrix grain.