Relations of magnetic and electrochemical anti-corrosion properties of (Zr, Ti)-doped NdCeFeB magnets with Ti content
Yuxuan Shao, Junjie Ni, Zhiwei Wang, Xuegeng Wang, Kai Xu, Bo Song, Yue Xu, Shutai Zhou, Tao Liu, Laima Luo
Abstract
Zr and Ti were co-doped into NdCeFeB sintered magnets to improve the magnetic and electrochemical anti-corrosion properties. Both performance are found closely associated with Ti content. At 0.15 wt%Ti, the sample shows higher coercivity without energy product loss compared to the Ti-free sample and other Ti additions, due to the matrix-phases refinement and optimized distribution of RE-rich phases. For this sample, its corrosion current density and charge transfer resistance are 1.94 μA/cm 2 and 1734 Ω•cm 2 in NaCl solution respectively, which exhibits obviously improved corrosion resistance in comparison with the Ti-free magnet. The charge transfer resistance has been increased by 45.6 %. The apparently improved corrosion resistance is mainly attributed to the decreased amount of active reaction channels and the enhanced protective effect of TiO 2 , arising from the increment of Ti-rich precipitates. When the content of Ti dopant exceeds 0.5 wt%, the beneficial effects of Ti are overshadowed by the harmful effect of the density reduction on anti-corrosion performance, and the charge transfer resistance decreased with further increasing the dopant content. The new findings provide a theoretical basis for improving physicochemical properties of NdCeFeB magnet.