• Korean Journal of Materials Research
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• v.7 no.4
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• pp.287-294
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• 1997

(NdㆍDy)-(FeㆍCoㆍAIㆍM)-B 합금에 Sn,Mo등을 첨가하여 그에 따른 미세구조와 열적안정성 및 자기적 특성 변화를 조사하였다. Sn과 Mo의 첨가는 (NdㆍDy)-(FeㆍCoㆍAIㆍM)-B 합금리본의 큐리온도를 크게 향상시켰으며 자기특성, 특히 보자력을 1KOe이상 증가시켰다. 그리고 이러한 현저한 보자력 증가는 입계형 defect인 disturbed grain boundary defect에 기인하는 것이라 판단되었다. 또한 Sn과 Mo 첨가원소는 irreversible loss를 각각 4%와 6% 감소시켜 리본자석의 열적안정성을 향상시켰다. 이는 Sn과 Mo의 첨가가 보자력을 크게 증가시켰기 때문이다. 한편 (NdㆍDy)-(FeㆍCoㆍAIㆍM)-B 리본자석들의 열저항온도(heat resistance temperature)는 irreversible loss와 직선관계를 이루었다.

• Journal of the Korean Magnetics Society
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• v.25 no.1
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• pp.4-9
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• 2015

This study was carried out to investigate a influence of humidity variation (%) on the magnetic properties and the surface flaws in the fabrication of Fe-based $Fe_{78}Si_9B_{13}$ amorphous alloy ribbon by Planar Flow Casting process. As a result, the size of the air pocket and the droplet which is observed in the contact surface and the free face of the amorphous alloy ribbon becomes large when the humidity increases and the size highly increases with the surface roughness at the same time. Especially, the surface roughness value which is made in the 65 % of the humidity is the lowest in the contact surface ($Ra=0.60{\mu}m$, $Rz=3.11{\mu}m$) and the free face ($Ra=0.47{\mu}m$, $Rz=3.00{\mu}m$). Also, in case of the soft magnetic property of the magnetic core which is made with the toroidal core of $23(OD)^*20(ID)^*20(H)$ size, in the sample of the amorphous alloy ribbon which is made in 65% of the humidity, the most excellent value is gained as $B_s(B_{700})=1.055T$, $H_c=0.083Oe$, permeability = 1,197 and core loss = 0.276W/kg.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.128-132
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• 2007

The thermal and magnetic properties of amorphous (FeCo)SiBNb ribbon alloys with high glass forming ability have been investigated. The glass forming ability was enhanced by Co substitution in amorphous ($Fe_{1-X}Co_X)_{72}Si_4B_{20}Nb_4$ alloys with the thickness of about $40{\mu}m$. With the increase in Co content, the temperature range of supercooled liquid phase increased indicating the high glass forming ability of the Co-added alloys. Further the ac permeability increased, and the core loss decreased considerably by Co substitution, while small change in $B_8$ (magnetic flux density at 800 A/m) was observed. The frequency characteristics of permeability deteriorated as compared to conventional amorphous ribbon alloys with the thickness of about $20\;{\mu}m$ due to the increased skin effect.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.154-159
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• 2002

Amorphous FeBSiNb alloy ribbons having bulk glass forming ability and high saturation magnetic flux density were produced by single-roller melt spinning apparatus in the thickness range of 22∼102㎛. With the increase of thickness, the coercive force and squareness ratio decreased, while maximum permeability and AC permeability increased. However electrical resistivity was almost constant. Furthermore refined and complex magnetic domain structure was observed in thicker ribbons owing to the change in internal magnetic anisotropy. For the alloy with the thickness of 81㎛, small coercive force of 24 mOe and high effective permeability of 12,000 at 1㎑ were obtained, those are considered to be better comparing to the conventional soft magnetic amorphous alloys (∼20 ㎛). The good soft magnetic properties of the thick FeBSiNb amorphous alloys were attributed to the decrease in surface pinning effect during wall motion, appearance of perpendicular anisotropy and resulted domain refinement.

• Analytical Science and Technology
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• v.8 no.3
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• pp.341-350
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• 1995

$Nd_{14}Fe_{80}B_6$ ribbon alloy was manufactured with using melt-spinning method and analyzed the magnetic properties according to the manufacturing conditions. The microstructure and magnetic properties of melt-spun ribbons are sensitively dependent on the quench rate and annealing conditions. As-quenched $Nd_{14}Fe_{80}B_6$ ribbons with optimum magnetic properties are obtained at wheel speed($v_s$) of about 20m/sec and over quenched ribbons show optimum magnetic properties at $v_s$=22m/see when annealed for 30 minutes at $600^{\circ}C$ under vacuum. The crystallization temperature($T_k$) of $Nd_2Fe_{14}B$ phase is about $595^{\circ}C$ in the DTA analysis.

• Electrical & Electronic Materials
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• v.1 no.4
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• pp.319-332
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• 1988

높은 포화자속밀도와 낮은 철손을 갖는 Fe/aub 80/B$_{12}$Si$_{8}$ 비정질합금을 일반열처리, 자장열처리시켜 그의 자기적특성과 자구구조와의 관계를 조사하였다. 이를 위하여 Fe$_{80}$B$_{12}$Si$_{8}$ 비정질리본을 단롤법으로 제작하여 결정화온도를 측정하였으며 측정된 결정화온도 이하의 여러 온도에서 30분간 Ar-gas 분위기하에서 일반열처리, 자장열처리를 행하였다. 이와같이 하여 준비된 시료의 자기적특성을 조사하기 위하여 D.C., A.C. Recorking Fluxmeter를 이용하였으며 자구구조는 Bitter method로 관찰하였다. as-cast 상태의 시료를 일반열처리함에 따라 내부응력이 완화되면서 maze자구가 점차 사라지고 wave형태의 180.deg.자구가 관찰되었다. 동시에 자화과정에 있어서 자기이력곡선은 Barkhausen jump가 없어 smooth하였다. 그리고 자장열처리시에는 as-cast 상태나 일반열처리에 비해 자기적특성이 현저하게 향상되었으며 이는 열처리를 행함에 따라 내부응력이 완화되면서 maze 자구가 없어지고 일축자기 이방성으로 리본길이방향에 평행하게 형성된 180.deg.자구에 기인하는 것이라 사료된다. 그리고 자장열처리의 경우, 폭방향으로 열처리한 리본의 자구폭은 길이방향으로 열처리한 리본의 폭보다 미세하였으며 전자의 이력손실이 후자의 것보다 더 컸다.다.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.173-179
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• 1997

Change in phases, microstructures, and magnetic properties by the variation of quench rate and heat treatment were investigated for melt-spun $Fe_{77}Pr_{15}C_8$ ribbons. The amorphization of as-spun ribbons increased as the quench rate increased. As a result, the ribbon quenched at 40 m/s was almost entirely amorphous. Similarly to cast alloys, the primary phase in crystalline ribbons quenched at 10 m/s was $\alpha$-Fe followed by the secondary $Fe_{17}Pr_2C_x$. Crystalline phases were still dominant in the ribbon spun at 20 m/s, but in this case crystallization of $Fe_{17}Pr_2C_x$ was remarkable with a little suppression of $\alpha$-Fe. At 30 m/s an amorphous phase obviously dominated in the as-spun ribbons with small fraction of crystals. Therefore, substantial amount of hard magnetic $Fe_{14}Pr_2C$ was not obtained from the as-spun state but, as in cast alloys, produced only by a solid-state transformation. Within a few minutes fine grains of $Fe_{14}Pr_2C$ were easily obtained at relatively low temperature when the degree of amorphization of as-spun ribbons was higher. The grain size of $Fe_{14}Pr_2C$ was well less than 1${\mu}{\textrm}{m}$. The ribbons quenched at 20 or 30 m/s yielded higher coercivities after heat treatment.

• Journal of the Korean Magnetics Society
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• v.5 no.4
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• pp.261-268
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• 1995

In order to investigate the origin of the asymmetric magnetization reversal effect, we studied the variation of magnetic hysteresis loops with the alloy composition in amorphous ferromagnetic alloy ribbons of ${(Fe_{1-x}Co_{x})}_{75}Si_{10}B_{15}$ system annealed at $380^{\circ}C$ for 16 hours in a zero field condition. The asymmetric magnetization reversal effect developed more strongly in amorphous ribbons having two metallic components than in ribbons having a single metallic component. The effect developed more strongly in ribbons showing a smaller value of the saturation mag¬netostriction. The development of the asymmetric magnetization reversal effect was affected by the ratio of two metallic components as well as the magnitude of the saturation magnetostriction.

• Proceedings of the Korean Magnestics Society Conference
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• 2011.06a
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• pp.166-166
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• 2011

• Proceedings of the Korean Magnestics Society Conference
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• 2012.05a
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• pp.135-135
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• 2012