Effect of Intergranular Phase Segregation on Magnetic Properties of NdFeB Magnet

다국어 초록 (Multilingual Abstract)

The hot deformed magnets were produced by hot-pressing of the as-cast ingots of Nd18Tb1Fe68Co5B8, Nd18Tb1Fe66.5Co5B8Cu1.5 and Nd18Tb1Fe66.5Co5B8Al0.75Cu0.75 alloys. The individual Cu addition decreased the melting temperature of the intergranular region phase from 606.5°C to 504.3°C leading to better wetting behaviour and easy rotation of magnetic grains during the hot deformation process and resulted in good magnetic properties. However, with Al addition, the intergranular composition was segregated into two phases and the Nd(Fe,Co,Al)2 phase was formed in addition to the Nd-rich phase at the interphase between grains during the hot deformation process. For this sample, grain alignment was poor and Hc, Br and (BH)max are 5.73 kOe, 5.75 kG and 9.94 MGOe respectively. The highest remanence and energy product are 7.25 kG and 13.65 MGOe respectively for the individual Cu added sample. It is suggested that the decrease in melting temperature of the intergranular phase leads to a better wetting behaviour to penetrate homogenously into the holes during hot deformation which resulted in the high density and the improvement of the magnetic properties.

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