Corrosion behavior of hot-pressed nanocrystalline NdFeB magnet in a simulated marine atmosphere

• The atmospheric corrosion of hot-pressed nanocrystalline NdFeB magnet was studied.
• The NaCl deposits greatly increased the corrosion of NdFeB, especially that of Nd.
• The Nd-rich phase of the nanocrystalline NdFeB has relatively higher stability.
• Nd2Fe14B decomposed into two phases with different Nd contents during corrosion.
• NaCl accelerated the formation of Nd(OH)3, making it enriched in corrosion films.

The corrosion behavior of hot-pressed nanocrystalline NdFeB magnet in a NaCl-induced atmosphere with relative humidity of 80% was investigated using SEM/EDS and XPS techniques. The NaCl deposits significantly increased the initiation and development of the corrosion of NdFeB, especially that of Nd. During corrosion process, Nd2Fe14B decomposed into several phases with different Nd contents. The preferentially corroded Nd came from the Nd-rich phase and the decomposition product of Nd2Fe14B which had high Nd content. Moreover, NaCl dramatically accelerated the formation of Nd(OH)3, making it rich in the corrosion films. Nd(OH)3 was unstable in the system. It gradually decomposed into Nd2O3.