Concurrent improvements in coercivity and corrosion resistance for Nd6Fe13Ga-reconstructed Nd–Fe–B sintered magnets

Abstract

The grain boundary phase with the chemical composition Nd₆Fe₁₃Ga in Nd–Fe–B sintered magnets has been the subject of considerable research interest due to its role in optimizing grain boundaries; however, it also presents a novel challenge regarding corrosion behavior. In this study, the regulation mechanism of Nd₆Fe₁₃Ga grain boundary-reconstructed magnets with concurrent improvements in coercivity and anti-corrosive properties was investigated. Results indicated that the formed non-ferromagnetic Nd₆Fe₁₃Ga phase and the modified Cu-rich continuous grain boundaries after Nd₆Fe₁₃Ga reconstruction contributed to the promotion of magnetic isolation and a reduction in the corrosion potential difference with the 2 : 14 : 1 phase. The underlying mechanisms of the corrosion behavior were further elucidated through in situ microstructural characterization and first-principles calculations of electron work functions for different phases. This study proposes an effective solution to enhance the magnetic properties and anti-corrosion simultaneously in Nd–Fe–B sintered magnets.