Effect of Nd-M (M = Al/Co) alloys addition on microstructures and magnetic properties of hot deformed CeFeB magnets

Abstract

In this study, the magnetic properties, thermal stabilities, elemental distributions and phase transition temperatures of hot deformed CeFeB magnets were investigated by adding 20 wt% of Nd85Al15 and Nd64Co36 alloys, respectively. The results revealed that the addition of low melting point alloys efficiently enhanced the comprehensive magnetic performance and thermal stability of the CeFeB magnets. The optimal magnetic properties were obtained with the addition of 20 wt% Nd85Al15. Compared to the original sample, the coercivity increased from 104 kA/m to 604 kA/m, and the maximum magnetic energy product increased from 8 kJ/m3 to 34 kJ/m3. The incorporation of Nd-Al/Co alloys effectively reduced the area fraction of the coarse grain region and facilitated a more uniform distribution of the RE-rich phase. TEM observations demonstrated that Nd partially replaced Ce, leading to the formation of (Nd, Ce)2Fe14B hard magnetic phase. Additionally, the analysis of the M–T curves indicated the presence of two Curie temperature points for Nd85Al15 and Nd64Co36 added CeFeB hot deformed magnets. The addition of Nd85Al15 improved the fluidity of the RE-rich phase, thereby enhancing the coercivity. Conversely, the incorporation of Nd64Co36 resulted in the entry of Co elements into the main phase, contributing to improved thermal stability.