•Ribbons with surface crystallization show a larger annealing temperature range.•Proper surface crystallization will decrease the P from 0.27W/kg to 0.20W/kg.•The crystallization process was driven ...by the diffusion and competitive processes.
In this study, Fe82Cu1Si4B11.5Nb1.5 nanocrystalline alloy ribbons with completely amorphous structure and surface crystallization were prepared using melt-spinning technique with wheel speeds of 45m/s, 35m/s and 25m/s. The effect of surface crystallization layers on the soft-magnetic properties, core loss and dynamic magnetization process were systematically investigated. Moreover, the permeability-frequency spectra were measured as a function of the AC magnetic field, ranging from 1 to 75A/m. It was found that decreasing the melt-spinning wheel speed can widen the annealing temperature range and the coercivity increases with the increase of surface crystallization. Excessive crystallization layers will increase the pinning field (Hp), which will lead to an increase of magnetic anisotropy constant K and eventually decrease the effective permeability. The crystallization mechanism of the Fe82Cu1Si4B11.5Nb1.5 nanocrystalline alloy ribbons with surface crystallization layers was discussed from the aspects of diffusion and competitive processes, which is helpful for further understanding the nanocrystallization process.
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•Mo addition improves formation of an amorphous phase in low vacuum atmosphere.•Mo containing alloys have better frequency properties than Mo free alloy.•Decreasing wheel speed can ...widen annealing temperature range for Mo-free ribbons.•All alloys exhibit a similar excellent soft-magnetic properties after annealing.
Fe82Cu1Si4B11.5Nb1.5−xMox (x=0, 0.75 and 1.5 at. %) nanocrystalline alloys were prepared using a melt-spinning technique and the effects of Mo content on thermal stability, soft magnetic properties and microstructure evolution were investigated. It was found that the Mo addition can improve the amorphous-forming ability and inhibit surface crystallization in a low vacuum atmosphere which may be due to better oxidative resistance. All the alloys exhibited excellent soft-magnetic properties with low coercivity of 8.9–10.8A/m, high effective permeability of 11,500–11,900 at 1kHz and high saturation magnetic flux density of 1.67–1.72T after annealing at optimal annealing conditions. In addition, the alloys containing Mo have better transient effective permeability stability with increase in frequency. Decreasing the melt-spinning wheel speed can widen the annealing temperature range for Fe82Cu1Si4B11.5Nb1.5 ribbon. Results indicate that these soft-magnetic nanocrystalline materials have good manufacturability for industrial production.
In order to utilize non-inert casting atmospheres to improve the glass forming ability (GFA) of Fe-based bulk glassy alloys, in this work, dependence of GFA, composition and soft magnetic properties ...on casting atmosphere species is observed for Fe77Mo2P10C4B4Si3 glassy alloy. Firstly, it was found that GFA can be significantly improved by some non-inert atmospheres, as when cast under N2/air/O2, its critical diameter can reach to 3.5 mm, which is larger than that of sample cast in inert Ar. Moreover, the component contents on the alloy surface vary greatly with the casting atmospheres while the whole bulk composition remains almost unchanged. In addition, this Fe-based glassy alloy exhibits identical soft magnetic properties regardless of the applied casting atmospheres. The mechanism for the positive effect of non-inert atmospheres on the GFA of Fe77Mo2P10C4B4Si3 glassy alloy may be involved with the surface properties of alloy liquid such as surface tension and the modified superficial composition.
•Dependence of GFA on casting atmosphere species is observed for a FeMoPCBSi alloy.•Its Dcr is improved to 3.5 mm by replacing Ar with non-inert casting atmospheres.•The component contents on alloy surface vary greatly with the casting atmospheres.•These alloys exhibit identical magnetic properties despite of atmosphere species.•The mechanism may be involved with the surface properties of alloy liquid.
In order to develop Fe-based nanocrystalline soft magnetic alloys with high saturation magnetic flux density (B s) and good manufacturability, the effect of the Nb content on the thermal stability, ...microstructural evolution and soft magnetic properties of Fe78-xSi13B8NbxCu1 (x = 0, 1, 2 and 3) alloys were investigated. It is found that proper Nb addition is effective in widening the optimum annealing temperature range and refining the alpha-Fe grain in addition to enhancing the soft magnetic properties. For the representative Fe76 Si13B8Nb2Cu1 alloy, the effective annealing time can be over 60 min in the optimal temperature range of 500-600°C. FeSiBNbCu nanocrystalline soft magnetic alloys with desirable soft magnetic properties including high B s of 1.39 T, low coercivity (H c) of 1.5 A/m and high effective permeability (mu e) of 21,500 at 1 kHz have been developed. The enhanced soft magnetic performance and manufacturability of the FeSiBNbCu nanocrystalline alloys are attributed to the high activated energy for the precipitation of alpha-Fe(Si) and the second phase. These alloys with excellent performance have promising applications in electromagnetic fields like inductors.
In order to develop Fe-based nanocrystalline soft magnetic alloys with high saturation magnetic flux density (
B
s
) and good manufacturability, the effect of the Nb content on the thermal stability, ...microstructural evolution and soft magnetic properties of Fe
78−
x
Si
13
B
8
Nb
x
Cu
1
(
x
= 0, 1, 2 and 3) alloys were investigated. It is found that proper Nb addition is effective in widening the optimum annealing temperature range and refining the α-Fe grain in addition to enhancing the soft magnetic properties. For the representative Fe
76
Si
13
B
8
Nb
2
Cu
1
alloy, the effective annealing time can be over 60 min in the optimal temperature range of 500–600°C. FeSiBNbCu nanocrystalline soft magnetic alloys with desirable soft magnetic properties including high
B
s
of 1.39 T, low coercivity (
H
c
) of 1.5 A/m and high effective permeability (
μ
e
) of 21,500 at 1 kHz have been developed. The enhanced soft magnetic performance and manufacturability of the FeSiBNbCu nanocrystalline alloys are attributed to the high activated energy for the precipitation of α-Fe(Si) and the second phase. These alloys with excellent performance have promising applications in electromagnetic fields like inductors.
