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The structure and magnetic properties of melt-spun multicomponent [Fe.sub.80-x][Sn.sub.x][P.sub.12][Si.sub.4][B.sub.4] (x = 1~8 at%) ribbons were investigated. The improvement of thermal stability was recognized with the replacement of Fe by 1~6 at% Sn in these alloys. The supercooled liquid region ([DELTA] [T.sub.x]) defined by the difference between crystallization temperature and glass transition temperature increases from 38.4 K as x = 1 to 46.6 K as x = 6. Optimal magnetic properties of [Fe.sub.80-x][Sn.sub.x][P.sub.12][Si.sub.4][B.sub.4] (x = 1~6 at%) amorphous ribbons annealed at 723 K for 600 s are: saturation magnetization 1.33 T; coercive force 2.86 A/m, maximum permeability 134000, core loss 0.07 W/kg (50 Hz, 1 T external magnetic field); Curie temperature is from 593 K to 600 K; the resistivity spans from 154 to 188 [micro][OMEGA]-cm. The alloys are potential in applications such as cores for power transformers. Index Terms--Bulk amorphous alloy, iron-based alloy, magnetic properties, tin addition.

The stress-impedance (SI) profiles were measured in Fe[sub 73.5]Cu[sub 1]Nb[sub 3]Si[sub 13.5]B[sub 9] ribbons annealed by Joule heating in the presence of longitudinal applied tensile stress of 100 MPa and the maximum SI ratio of 350% is observed. It was found that the large SI effect is the result of induced transverse magnetic anisotropy. We present a model that explains the variations of transverse magnetic anisotropy on SI effect. The model is based on the skin effect and on the magnetization rotation due to the applied tensile stress and the ac driving current. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Crystallization and associated magnetic domain structure of [Fe.sub.73.5][Cu.sub.1][Nb.sub.3][Si.sub.13.5][B.sub.9] amorphous ribbons have been investigated in in-situ annealing studies by electron transmission microscopy (TEM). Two stages of crystallization, which occurred at 380 [degrees] C and 650 [degrees] C, have been observed. The crystals associated with these temperatures are spherical nuclei with diameters less than 5 nm or clusters of ultrafine grains whose diameters are in the range of 15-20 nm respectively. The products formed at both stages are identified as the [Alpha]-Fe(Si) phase. The magnetic domain structure of the as-quenched specimen is composed of large and simple domains. There is no evident change in domain structure upon the onset of the first crystallization. However, the second stage of crystallization leads to emergence of magnetic ripple. The origin of magnetic ripple is discussed within the framework of the random anisotropy model. From the analysis, effective uniaxial anisotropy [is less than] k [is greater than] in the nanocrystalline alloy may be considered as local random anisotropy and is therefore likely to be the cause of the magnetic ripple. The estimated mean wavelength, [Lambda], of the magnetic ripple is approximately 160 nm.

Study of the dependence of magnetic properties of sintered 40Cedidymium-Fe-B magnets on their Si, Co and Dy(sub 2)0(sub 3) contents reveals that a decrease in H(sub c) and T(sub c) is caused by Ce in the magnets. The study is performed using transmission electron microscopy which determines the microstructure of magnetic materials. Decrease in H(sub c) and T(sub c) can be attributed to the presence of smaller additive elements.

The influences of Si, Co and Dy2O3 on the magnetic properties of CeDidymium-Fe-B inexpensive sintered magnets were investigated. The CeDidymium (CeDidym) synthesized for this study had the composition of 40Ce-50Nd-10Pr in wt%. Two series of alloys having the composition of CeDidym16.5Fe77-xSixB6.5 and CeDidym16.5Fe73-yCoySi4B6.5, where 0 is less than or equal to x is less than or equal to 8 and 0 is less than or equal to y is less than or equal to 30, have been prepared. It is found that the intrinsic coercivity iHc and the Curie temperature T(sub c) were increased from 5.1 kOe and 261 degrees C for x = 0 to 7.2 kOe and 286 degrees C for x = 8 respectively. The addition of 10 at % of Co causes a substantial increases in T(sub c) from 275 degrees C to 350 degrees C. The intrinsic coercivity of the (Si, Co)-containing magnets was further improved by Dy2O3 addition. The magnetic properties of the sintered magnets made from the CeDidym16.5Fe63Co10Si4B6.5 powder blended with 3 weight percent Dy2O3 are Br = 10.9 kG, iHc = 9.2 kOe, (BH)max = 28.2 MGOe and T(sub c) = 350 degrees C.

Abstract: Al content on the influence of glass forming ability and magnetic properties of nanocrystalline (Fe83.3Si4B8P4Cu0.7)100− x Al x (x =0∼1.25at.%) alloy was investigated in our work. Experimental results show that addition of 0.5at.% Al is effective in improving the glass forming ability of Al-free alloy and thus amorphous precursor prepared by industry-grade raw materials can be obtained. Meanwhile, the addition of Al is beneficial in decreasing coercive force and maintaining high saturation magnetization above 180emu/g, which makes Fe–Si–B–P–Cu–Al alloy a promising soft magnetic material in potential applications. [Copyright &y& Elsevier]