Innovative Melt-Spinning Technique for Ferromagnetic Amorphous Ribbons
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INNOVATIVE MELT-SPINNING TECHNIQUE FOR FERROMAGNETIC AMORPHOUS RIBBONS H. Y. Yu*, D. R. Huang", P. C. Yao** and S. E. Hsu** *Chung Cheng Institute of Technology, Tachi, Taiwan 335, R.O.C. "*Chung Shan Institute of Science and Technology, Lungtan, Taiwan 325, R.O.C. ABSTRACT A new melt-spinning technique (field quenching) for ferromagnetic amorphous ribbon is suggested to produce better magnetic properties than conventional as-quenched amorphous ribbon. An external field is applied during the quenching either parallel or perpendicular to the casting direction. The magnetic moment and initial permeability are increased when the field direction is parallel to the casting direction. These effects are opposite when these two directions mentioned are perpendicular to each other. INTRODUCTION The amorphous alloy or the glassy metal produced by continuous meltquenching processes are recognized as important materials for industrial applications as well as for fundamental scientific research. Some of them show attractive engineering characteristics, such as soft magnetic properties, high strength or good corrosion resistance, which are equivalent to or superior to those of conventional crystalline materials. The occurrence of ferromagnetism in amorphous materials was predicted on a theoretical basis by Gubanov [1]. The first strongly ferromagnetic glassy metal obtained by liquid quenching was FeaoP12,sC7.s [2]. Recent studies of magnetic behavior of glassy metal have been centered on glassy ribbon because of their potential industrial applications [3]. The ferromagnetic glassy metal ribbons having general composition, transition metals -20% metalloid, exhibit low coercive force Hc -0.1-0.001 Oe. and high permeabilities comparable to soft magnetic alloys. A number of investigators have shown that significant improvement in magnetic properties of glassy metal can be obtained by field annealing [4-8]. However, there is a drawback effect of heat treatment, which causes embrittlement of ironcontaining amorphous alloys [9]. In some cases, the alloys become so brittle after annealing that they can not be handled without breaking. Since the combination of excellent magnetic and mechanical properties is the most attractive feature of the amorphous alloys, the loss of ductility by annealing is a serious problem. Our purpose in this paper is to report a new melt-spinning technique with the result that is believed to be a highlight and possibly can produce amorphous ribbons with better soft magnetic properties than conventional as quenched ribbons. The method is defined as "Field Quenching Technique." EXPERIMENT PROCEDURE The castings were carried out in air on a rotating pure copper wheel with the diameter of 29.5cm and 2060 rpm rotating speed which gave a linear surface speed of 3187.2cm/s. The quartz crucibles had retangular slot openings of 0.35cm by 20cm. The crucible is held vertically and displaced about 3.5cm away from the vertical central line of the wheel, and the gap between crucible bottom surface and wheel surface was typic
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