Effects of flash annealing and external magnetic field on magnetic properties of relatively high Nd content (37% by weight) NdFeB alloy

Post modifications such as alloying element addition and/or heat treatment are applied to improve the magnetic properties of NdFeB permanent magnets. In this study, effects of external magnetic field and flash annealing at different temperatures (680 °C and 710 °C) and durations of 5 and 10 min on the magnetic properties of relatively high Nd content (37 wt.%) NdFeB magnet alloys were investigated. Melt spinning method was used in production of the NdFeB magnet alloys. Heat treatment was applied to various NdFeB magnet ribbons at 680 °C and 710 °C temperatures for 5 and 10 min by the flash annealing at heating and cooling rates of 300 K/s. In addition, before vibrating sample magnetometer tests, various samples were magnetized under an external magnetic field of 5 Tesla. After melt spinning, semi-amorphous structure was obtained and Nd2Fe14B hard and α-Fe soft magnetic phases were crystallized at nanoscale by flash annealing. These crystallizations formed between approximately 350 °C and 430 °C. After the flash annealing, residual amorphous structures were observed without complete crystallization. The highest remanence and coercivity were obtained in the sample flash annealed for 10 min at 710 °C, 57.64 emu/g and 10,419.07 Oe, respectively. The maximum energy product improved thanks to the high remanence and coercivity, important for the NdFeB magnets resulted in a high value of 87.79 kJ/m 3 in the same sample. This flash annealing procedure provides a cost-effective and simple platform to improve the magnetic features of NdFeB magnets.