L.C. Wu, Y.H. Li, K. Yubuta, A.N. He, Y.Zhang, W.Zhang. Journal of Magnetism and Magnetic Materials, 2020, 497.

Abstract:

The effects of Cu and Nb additions on the structure and magnetic properties of a Fe₈₇B₁₃ alloy in melt-spun and annealed states were investigated. Increase in Cu content from 1.0 to 1.7 at.% changes the melt-spun Fe_87-xB₁₃Cu_x alloy ribbons from a single amorphous phase to a composite of high-number-density nano-order α-Fe phase with an average grain size (D_α-Fe) of 12.1 nm dispersing in the amorphous matrix. The crystallized structure after annealing gets refined with increasing the Cu content, and a small D_α-Fe of 18.1 nm is obtained for the Fe_85.3B₁₃Cu_1.7 alloy, which possesses a low coercivity (H_c) of 32.6 A/m and high saturation magnetic flux density (B_s) of 1.87 T. Minor addition of Nb reduces the D_α-Fe in melt-spun Fe_85.3-yB₁₃Cu_1.7Nb_y alloys but not obviously lowers the number density, while 3 at.% Nb makes the formation of fully amorphous phase. The D_α-Fe in the crystallized alloys is decreased to 15.3 nm by alloying 2 at.% Nb, but increased to 31.4 nm with 3 at.% Nb. The Fe_83.3B₁₃Cu_1.7Nb₂ nanocrystalline alloy exhibits a lower H_c of 9.5 A/m combined with high B_s and effective permeability at 1 kHz of 1.75 T and 15000, respectively. The combined effects of competitive growth of the pre-existing nano-order α-Fe particles and Nb-inhibited atoms diffusion contribute to the refinement of the nanocrystalline structure.

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