Microstructure and magnetic properties of Fe81.3Si4B13Cu1.7 nanocrystalline alloys with minor Nb addition
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The amorphous matrix containing dispersive high number density (Nd) α-Fe nuclei with average grain sizes (D) of 4.3–6.2 nm was formed in the melt-spun Fe81.3–xSi4B13Cu1.7Nbx (x = 0–2) alloys, and the Nd and D values reduce with increase in the Nb content. The fine nanocrystalline structure with α-Fe grains of 14.0–21.6 nm in size was obtained for the annealed alloys, which showed high saturation magnetic flux density of 1.60–1.77 T and low coercivity (Hc) of 7.1–17.0 A/m. Addition of minor Nb significantly expands the optimum annealing temperature range for obtaining good soft magnetic properties, while coarsens the α-Fe grains, leading to a slight increase in the Hc. The mechanism of the effect of Cu and Nb elements on the structure and magnetic properties was discussed in terms of the formation and growth of the α-Fe nuclei of the alloys.
KeywordsFe-based nanocrystalline alloy Soft magnetic property Cu content α-Fe nuclei Nb alloying
This research was supported by the National Key Research and Development Program of China (Grant No. 2017YFB0903903) and the National Natural Science Foundation of China (Grant Nos. 51571047, 51771039).