Effect of ambient gas pressure on the microstructure and magnetic properties of melt-spun Nd10Fe83Zr1B6 nanocomposite

The effects of ambient gas pressure on the surface morphology, microstructure and magnetic properties of melt-spun Nd10Fe83Zr1B6 ribbons have been studied. It is shown that melt-spinning at reduced pressures can effectively prevent the formation of gas pockets at the roll-contacted surfaces of ribbons, making the cooling rates of ribbons more uniform. At reduced pressures, the microstructure of ribbons is more homogeneous and fine-grained. However, due to the thermal exchange of free surface with the ambient gas, the lowest gas pressure does not necessarily lead to the highest magnetic properties. After annealing, the alloy Nd10Fe83Zr1B6 produced at pressure 0.4 × 105 Pa exhibits the optimal magnetic properties of Br = 0.95 T, iHc = 850 kA/m and (BH)max = 140 kJ/m3, as compared to 0.85 T, 710 kA/m and 112 kJ/m3 produced at pressure 1.0 × 105 Pa.