Microstructure and magnetic properties of surfactant-assisted ball milling NdFe8Co2Mo2 powders and their nitrides

The NdFe ₈Co ₂Mo ₂ alloy ribbons were prepared by melt-spinning. The powder was prepared through surfactant-assisted ball milling, followed by nitriding to produce the NdFe ₈Co ₂Mo ₂N _x alloy. The alloy ribbons grain size decreases as the copper roller speed increases. At the speed of 30 m/s, a pure 1:12 phase alloy ribbons were produced. The grain size decreases with increasing the ball milling time, but the composition phases almost unchanged of the alloy powder. The grain size refine after nitriding, but the grain volume expands when the nitriding temperature exceeds 500 °C. With increasing ball milling time and nitriding temperature, the remanence (M _r) and coercivity (H _c) of the alloy powder increase first and then decrease. The alloy powder obtained from ball milling for 3 h after nitriding at 475 ℃ for 3 h, resulting in M _r was 44.43 Am ²/kg, H _c was 0.434 T, and saturation magnetization (M _s) was 74.89 Am ²/kg.