Effects of Al on the magnetic properties of nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloys

Abstract

The effects of Al on the soft magnetic properties of nanocrystalline Fe73.5−xAlxCu1Nb3Si13.5B9 alloy ribbons are investigated in the composition range of 0≤x≤1.0. The relative initial permeability at 1 kHz is found to increase by the addition of Al, and reaches the peak value at x=0.1. The coercivity decreases, rather significantly, with the Al content in the whole composition range investigated in the present work, the values of the coercivity being 12.5 mOe at x=0 and 9.3 mOe at x=1.0. The magnetic induction at an applied field of 10 Oe, however, decreases moderately by the introduction of Al, possibly due to the dilution effect. The improvement in the soft magnetic properties is considered to result from the reduction in the grain size of the α Fe-Si solid solution phase of the Al-added alloy ribbons, which has been observed by transmission electron microscopy. Another factor may be due to the decrease in the intrinsic magnetocrystalline anisotropy K1 as Al is added to the alloy.

Low-field hysteresis in disordered ferromagnets

“…It has been reported that the initial susceptibility in several cases displays a peak as the heat treatment or the alloy composition are varied [10][11][12][13]. The peak is usually associated to changes in the microstructure, which induce a competition between the disorder present in grain anisotropies and inter-grain interactions mediated by the amorphous matrix [10].…”

“…Successive developments and improvements have been devoted to establish precise links between Néel random potential and the material microstructure [6][7][8][9], but in several cases the issue is still unsettled. For instance, the initial permeability of nanocrystalline materials typically displays a peak as a function of the grain size [10], heat treatment [11,12] or alloy composition [10,13]. This behavior can be associated to changes in the disordered microstructure, but can not be accounted for by Néel theory that predicts a monotonic dependence of a on the disorder width [5].…”

Effect of Ca and Al Additions on the Magnetic Properties of Nanocrytalline Fe-Si-B-Nb-Cu Alloy Powder Cores

“…The Ca and Al containing alloy showed the relatively large temperature gap (ΔT) between T x1 and T x2 , compared to the other alloys. Based on the results, it can be concluded that Ca and Al additions generally improve the thermal stability of the nanocrystalline structure of the α-Fe(Si) phase [34][35][36][37][38].…”

Microstructural Change and Magnetic Properties of Nanocrystalline Fe-Si-B-Nb-Cu Based Alloys Containing Minor Elements

“…Lim et al [19] and Zorkovska et al [20] have found that the T x1 of Fe 73.5-x Si 13.5 B 9 Cu 1 Nb 3 Al x amorphous alloy decreases with increase of Al. Warren et al [21] have investigated the spatial distribution of atoms in the nanocrystalline Fe 71.5 Si 13.5 B 9 Cu 1 Nb 3 Al 2 alloy through a three-dimensional atom probe, and found the decrease of T x1 is attributed to the solution of Al into the Cu clusters, which enhances the precipitation of nanocrystals.…”