Effect of Nb Addition on the Structure, Magnetic Properties and Annealing Embrittlement of A FeBCu Nanocrystalline Alloy

To improve annealing process and decrease annealing embrittlement of FeBCu nanocrystalline alloys, the effect of Nb content on the structure, thermal properties, crystallized structure, magnetic properties and brittleness of melt-spun Fe_86-xB₁₃Cu₁Nb_x (x = 0~6) alloy ribbons was investigated by using X-ray diffraction, transmission electron microscopy, differential scanning calorimeter, vibrating sample magnetometer, and bending test method. The results show that the increase of Nb content enhances the thermal stability of amorphous phase, and refines α-Fe grains, improves soft magnetic properties as well as reduces the annealing embrittlement of the annealed alloys. The addition effect on the structure and properties is significant when the Nb content exceeds 2 at.% and becomes moderate when Nb content ≥ 5 at.%. The decreased annealing embrittlement of the nanocrystalline alloys is mainly due to the reductions of both grain size and volume fraction of the α-Fe phase.