Phase structure of Al doped Ce-rich alloys and its effect on magnetic properties of sintered Ce-Fe-B magnets

In this article, the phase constitution, microstructures and melting points of Ce35.58Fe63.47-xAlxB0.95 alloys (at.%; x = 0, 3, 5, 10) have been investigated. It indicated that the Ce-rich alloy with x = 0 was mainly composed of CeFe2, Ce2Fe17 and γ-Ce phases. The AlCe3 phase was found in the alloy with x = 3. The microstructures and phase distribution characteristics of the alloys have obviously changed with increasing Al content (x = 5,10). The volume fractions of CeFe2 and Ce2Fe17 decreased. Some dispersed Ce-Al eutectic structures with low melting point were found in the alloy with x = 10. It is showed that the melting points of Ce-rich alloys have a decreasing tendency with increasing Al content, the melting points reduced from 942 °C at x = 0–856 °C at x = 10. Furthermore, the influences of the Ce35.58Fe53.47Al10B0.95 alloy addition on the microstructures and magnetic properties of sintered Ce-Fe-B magnets, were also discussed. The remanence Br slightly decreased, while the intrinsic coercivity Hcj, maximum energy product (BH)m and squareness Hk/Hcj (the ratio of knee coercivity to intrinsic coercivity) of the magnets had significant improvements, and these indexes increased by 8%, 22%, 24%, respectively.