Takao Mizushima

Influence of Si addition on thermal stability and soft magnetic properties for Fe-Al-Ga-P-C-B glassy alloys

The thermal stability of the supercooled liquid region (ΔTx), defined by the difference between crystallization temperature (Tx) and glass transition temperature (Tg), and soft magnetic properties were investigated for Fe70Al5Ga2P12.65−xC5.75B4.6Six(x=0–4) and Fe77Al2.14Ga0.86P11−xC5B4Six(x=0–3) glassy alloys. The thermal stability, glass forming ability and effective permeability (μe) at 1 kHz are improved with the replacement of P by 1–3 at. % Si for Fe70Al5Ga2P12.65−xC5.75B4.6Six and by 1–2.6 at. % Si for Fe77Al2.14Ga0.86P11−xC5B4Six. The ΔTx and the maximum thickness for glass formation (tmax) reach maximum values of 60 K and 280 μm, respectively, for Fe70Al5Ga2P12.65−xC5.75B4.6Six and 34 K and 220 μm, respectively, for Fe77Al2.14Ga0.86P11−xC5B4Six at Si(at. %)/(Si(at. %)+P(at. %))=0.24. Core losses for Fe77Al2.14Ga0.86P8.4C5B4Si2.6 glassy alloy is much lower than that for amorphous Fe–Si–B alloy at the sheet thickness more than 70 μm. Therefore, it can be said that the Fe–Al–Ga–P–C–B–Si glassy alloys...

Preparation of new amorphous powder cores using Fe-based glassy alloy

So as to obtain a new metallic powder core with constant permeability and low core loss up to higher frequency range, we have tried to prepare the amorphous alloy powder cores by using the Fe/sub 70/Al/sub 5/Ga/sub 2/P/sub 9.65/C/sub 5.75/B/sub 4.6/Si/sub 3/ glassy alloy powders that have a wide supercooled liquid region (/spl Delta/T/sub x/) below the crystallization temperature (T/sub x/). The Fe-based glassy alloy powder core (FGAPC) had a constant permeability of about 110 up to 10 MHz, which is comparable to commercial cores. The FGAPC also had a lowest core loss of 610 kW/m/sup 3/ at B/sub m/=0.1 T and f=100 kHz in any other metallic powder cores. These excellent magnetic properties of the FGAPC in a higher frequency range are presumably due to an extremely low coercive force (H/sub c/) derived from sufficient elimination of internal stress by annealing at near the /spl Delta/T/sub x/ and its higher electrical resistivity (/spl rho/) of about 1.60 /spl mu//spl Omega/m for the Fe/sub 70/Al/sub 5/Ga/sub 2/P/sub 9.65/C/sub 5.75/B/sub 4.6/Si/sub 3/ glassy alloy. These excellent magnetic properties of the FGAPC, therefore, allows us to expect that this core will be suitable for high frequency drive magnetic devices such as a choke coil, reactor and so on.

Thermal stability and magnetic properties of Fe-Al-Ga-P-C-B-Si amorphous thick sheets

The structure and magnetic properties of melt-spun multicomponent Fe/sub 72/Ga/sub 2/Al/sub 5/P/sub 11-x/C/sub 6/B/sub 4/Si/sub x/ (x=0-10) alloy sheets were investigated. The increases in the thermal stability and glass forming ability, and the improvement of the soft magnetic properties were recognized with the replacement of P by 1-2 at% Si. The supercooled liquid region (/spl Delta/T/sub x/) defined by the difference between crystallization temperature (T/sub x/) and glass transition temperature (T/sub g/) increases from 51 K for the Fe/sub 72/Al/sub 5/Ga/sub 2/P/sub 11/C/sub 6/B/sub 4/ alloy to 65 K for the Fe/sub 72/Al/sub 5/Ga/sub 2/P/sub 9/C/sub 6/B/sub 4/Si/sub 2/ alloy, and then decreases with increasing Si content. The maximum thickness for glass formation (t/sub max/) also increases from 140 /spl mu/m for the Fe/sub 72/Al/sub 5/Ga/sub 2/P/sub 11/C/sub 6/B/sub 4/ alloy to 190 /spl mu/m for the Fe/sub 72/Al/sub 5/Ga/sub 2/P/sub 9/C/sub 6/B/sub 4/Si/sub 2/ alloy. The increases in /spl Delta/T/sub x/ and t/sub max/ are presumably because of increased agreement with three empirical rules for glass formation. The soft magnetic properties at the thickness of over 70 /spl mu/m are also improved by the replacement of 1-2 at% Si. The magnetic properties for the Fe/sub 72/Al/sub 5/Ga/sub 2/P/sub 9/C/sub 6/B/sub 4/Si/sub 2/ amorphous alloy with the thickness of 190 /spl mu/m after optimum annealing (623 K/spl times/1.8 ks) are 169/spl times/10/sup -6/ Wbmkg/sup -1/ for saturation magnetization (/spl sigma//sub s/), 1.0 A/m for coercive force (H/sub c/), and 9000 for permeability (/spl mu//sub e/) at 1 kHz. It is therefore expected that the Fe-based amorphous alloy containing 2 at% Si is widely used as a bulk amorphous material with good soft magnetic properties.

Structure and magnetic properties of bulk Fe-Al-Ga-P-C-B-Si glassy alloys in a ringed form prepared by copper mold casting

Structure and soft magnetic properties were investigated for a bulk glassy Fe/sub 70/Al/sub 5/Ga/sub 2/P/sub 10.05/C/sub 5.75/B/sub 4.6/Si/sub 2.6/ alloy in a ring shape form with an outer diameter of 10 mm, an inner diameter of 6 mm and a thickness of 1 mm prepared by copper mold casting. The bulk sample consisted of only a single amorphous phase. The supercooled liquid region, saturation magnetization, and Curie temperature for the bulk sample are about 60 K, 1.2 T, and 620 K, respectively, in agreement with that of the corresponding amorphous alloy ribbon, The maximum permeability and the coercivity for the bulk sample are about 110000 and 2.2 A/m. These good soft magnetic properties of the bulk glassy alloy are presumably due to a higher degree of structural homogeneity resulting from its high glass-forming-ability. Therefore, these excellent soft magnetic properties as well as the very high castability for the Fe-Al-Ga-P-C-B-Si glassy alloy allows us to expect that this glassy alloy will be used as an engineering magnetic material.

SOFT MAGNETIC PROPERTIES OF FE BASED AMORPHOUS THICK SHEETS WITH LARGE GLASS FORMING ABILITY

The thermal stability of the supercooled liquid, glass forming ability (GFA) and magnetic properties were examined for amorphous Fe72−xAl5Ga2P11C6B4Six, Fe72Al5Ga2P11−xC6B4Six, and Fe72Al5Ga2P11C6−xB4Six alloys. The increases in the thermal stability and GFA and the improvement of the soft magnetic properties were recognized in the replacements of P by 1 to 2 at. % Si and of C by 1 at. % Si. The supercooled liquid region ΔTx defined by the difference between Tx and Tg increases from 53 K for Fe72Al5Ga2P11C6B4 to 58 K for Fe72Al5Ga2P11C5B4Si1. The maximum thickness for glass formation (tmax) by copper mold casting also increases from 1 mm for the Fe–Al–Ga–P–C–B alloy to 3 mm for the Fe72Al5Ga2P10C6B4Si1 alloy. The increases in ΔTx and tmax are presumably because of the increase in the degree of the satisfaction of the three empirical rules for glass formation. The soft magnetic properties are also improved by the replacement of 1% Si through the increase in the squareness ratio of B–H loop (Br/Bs) and the ...

Low core losses and soft magnetic properties of Fe-Al-Ga-P-C-B-Si glassy alloy ribbons with large thicknesses

The structure, soft magnetic properties, and core losses were investigated for a Fe77Al2.14Ga0.86P8.4C5B4Si2.6 glassy alloy with a sheet thickness in a wide range from 30 to 240 μm prepared by the melt-spinning technique. The maximum thickness (tmax) for glass formation and the thermal stability (ΔTx) of the supercooled liquid region defined by the difference between the crystallization temperature (Tx) and the glass transition temperature (Tg) are about 220 μm and 35 K, respectively. The saturation magnetization (σs) of this glassy alloy is about 1.5 T. The effective permeability at 1 kHz is as high as 12 000 in a thickness of 30 μm and it maintains high values above 4400 up to a thickness of tmax. The coercive force is kept at a low level, under 3 A/m up to tmax. This glassy alloy also shows low core loss values of 0.1–0.3 W/kg at f=50 Hz and Bm=1.0 T in the thickness from 30 to 220 μm. On the other hand, a Fe78Si9B13 amorphous alloy shows almost the same low core losses as that of the glassy alloy only...

Structure and magnetic properties of Fe-based glassy alloys

Abstract A multicomponent Fe 73 Al 5 Ga 2 P 11 C 5 B 4 alloy has a wide supercooled liquid region before crystallization and ferromagnetism at room temperature. Structure and magnetic properties of melt-spun Fe 73 Al 5 Ga 2 P 11 C 5 B 4 alloys with the thickness from 15 to 230 μm were investigated. The critical thickness for Fe based glassy alloy to maintain single amorphous phase is about 135 μm. Saturation magnetization (σ s ), coercive force ( H c ) and effective permeability (μ c ) at 1 kHz indicate constant value, 1.8 × 10 −4 Wbm kg −1 , 3 A m −1 and 8000 respectively, with the sample thickness of 135 μm. The magnetic properties of Fe based glassy alloy annealed at 773 K for 600 s are compared with that of Fe 78 Si 9 B 13 amorphous alloy. It is expected that the Fe based glassy alloy will be amorphous bulk material which has good soft magnetic properties.

Structure and Soft Magnetic Properties of Bulk Fe-Al-Ga-P-C-B-Si Glassy Alloys Prepared by Consolidating Glassy Powders

With the aim of developing a bulk glassy Fe-based alloy with good soft magnetic properties by the powder metallurgy technique, we have applied the pulse current sintering technique to a Fe 70 Al 5 Ga 2 P 9.65 C 5.75 B 4.6 Si 3 glassy alloy powder with a large supercooled liquid region of 60K before crystallization. The existence of the supercooled liquid region was found to enable us to form a bulk glassy alloy with a very high relative density of 99%. The resulting bulk glassy alloy exhibits good soft magnetic properties, i.e., 1.17T for flux density at a field of 800A/m, 12.0A/m for coercive force and 8000 for maximum permeability which are much superior to those for the bulk amorphous Fe-Si-B alloy prepared by the same sintering method. The much better soft magnetic properties for the multicomponent Fe-based bulk alloy are attributed to the combination of the high relative density and the unique amorphous structure with the features of high packing density and long-range homogeneous atomic configurations. The first success of forming the bulk amorphous alloy with good soft magnetic properties by the powder metallurgy technique is expected to enable us to use as practical soft magnetic materials.

Compositional Dependence of Thermal Stability and Soft Magnetic Properties for Fe-Al-Ga-P-C-B Glassy Alloys

Structure, glass forming ability and soft magnetic properties for Fe-Al-Ga-P-C-B glassy alloy system were investigated in the compositional range of Fe from 69 to 78 at%, (Al+Ga) from 2 to 12 and (P+C+B) from 17 to 28. The saturation magnetization (σ 5 ) rises gradually with increase of Fe concentration. The maximum value of 70K for supercooled liquid region (ΔT x =T x -T g , T x : crystallization temperature, T g : glass transition temperature:) and the maximum thickness of 180 μm for glass formation (t max ,) are found in the composition range around Fe=70at% and (Al+Ga)=7at%. The highest permeability (μ c ) of 20,000 at 1kHz and the lowest coercive force (H c ) of 2 A/m at the sample thickness of 30 μm can be also obtained at this composition. It was ascertained that the composition regions to yield the maximum glass forming ability and lowest magnetostriction were in agreement with that in which the most excellent soft magnetic properties were yielded. This results allow us to assume that the excellent soft magnetic properties for this glassy alloy system in the limited composition range are presumably due to high structural homogeneity resulting from significantly high glass-forming ability.

Thermal Stability And Magnetic Properties Of Fe-Al-Ga-P-C-B-Si Amorphous thick sheets with wide super cooled Liquid Region

Introduction I t is well known that the production of Fe-based amorphous alloys had been limited to the melt-spinning method because of the necessity of high cooling rates resulting from their low glass-forming ability. It is therefore difficult to prepare Fe-based amorphous alloy ribbons with large thickness indicating good soft magnetic properties. For instance, the maximum thickness(tmax) to form a single amorphous phase for Fe-Si-B amorphous ribbons is below 100pm[l]. Recently, we have reported that an Fe~3Al5Ga~P1 iCsB4 glassy alloy ribbon has a wide supercooled liquid region exceeding 50K before crystallization[2] and the t m a x of 135pm and indicates good soft magnetic properties as compared with FemSisBi3[1]. With the aim of preparing a much thicker amorphous ribbon, Si was added into the Fe-AI-GaP-C-B alloy system . This paper intends to present the influence of Si addition on their maximum ribbon thickness and soft magnetic properties.