• 한국자기학회지
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• 제5권5호
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• pp.772-777
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• 1995

The effect of small addition of Nb on the electrical resistivity and Hall coefficient of the amorphous $Fe_{83}Zr_{7}B_{10}$ alloy and annealed ones below the crystallization temperature were investigated, which has been considered to be suitable for high frequency core material. At room temperature, their resistivities $\rho$ and the spontaneous Hall coefficients $R_{s}$ are $~1.6\;{\mu}{\Omega}m$ and $~3{\times}10^{-8}m^{3}/As$, respectively. $R_{s}$ and $\rho$ are decreased with increasing temperature from 100 K to room temperature. Side-jump effect was adopted to analyze the effect of the small variation of concentration and annealing. The quantity of $R_{s}/{\rho}^{2}$ at room temperature, which is directly related to the electronic structure of the mother alloy, remained almost a constant except as quenched one as it can be predicted from the side-jump effect. We suggested the temperature dependence of $R_{s}/{\rho}^{2}$ can be compared to Ms{T}.

• 한국재료학회지
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• 제12권4호
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• pp.259-263
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• 2002

Three different ribbons of amorphous $Til_{1-x}Be_x$ alloys such as $Ti_{0.59}Be_{0.41},\;Ti_{0.61}Be_{0.39}\;and\;Ti_{0.63}Be_{0.37}$ were made by melt-spinning method to be used as brazing filler metals for joining Zircaloy-4 nuclear fuel cladding tubes, and their crystallization behavior as well as microstructure of the brazed zone were examined. The crystallization behavior was investigated in teams of thermal stability, crystallization temperature and activation energy. The crystallization of the $Ti_{1-x}Be_x$ alloys proceeded in two steps by the formation of ${\alpha}$-Ti at a lower temperature and of TiBe at a higher temperature. The crystallization temperature and activation energy of $Ti_{1-x}Be_x$ alloys were higher and larger than those of $Zr_{1-x}Be_x$ alloys and PVD Be. Those resulted thinner joining layer with $Ti_{1-x}Be_x$ alloys, which kept sound thickness of Zircaloy-4 nuclear fuel cladding tubes after brazing. But in the brazed zones made by $Ti_{1-x}Be_x$ filler metals, a little solid-solution layers composed of Zr and Ti were formed toward the Zr cladding tube and Zr was detected in the brazed zones. Microstructure of brazed zone was changed from globular to dentrite with decreasing Be content in the $Ti_{1-x}Be_x$ filler metal.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.90-91
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• 2003

Amorphous magnetic materials with competing magnetic interactions are the subject of current interest. Critical behaviour studies have been performed in order to understand the nature of the phase transition at the Curie point (T$\sub$c/) and type of magnetic ordering below the T$\sub$c/. In some cases there exists a temperature interval in which the magnetic system consists of ferromagnetic grains separated by the paramagnetic interlayers. Magnetic properties of nanoparticles embedded in amorphous matrix also are the subject of recent interest. While these materials exhibit excellent soft magnetic properties at room temperature, some of them have been found to be superparamagnetic in the temperature range above the T$\sub$c/ of the matrix. Thus the role of different magnetic phases in the intergrain magnetic coupling can possibly be taken apart in a sufficiently broad temperature range and investigated separately. In particular materials with competing magnetic exchange interactions show characteristics of enhanced magnetoresistance and softer magnetic properties when magnetic nanocrystals are dispersed in amorphous matrix. We expect careful magnetic measurements in the vicinity of T$\sub$c/ would throw some light on magnetic behaviour of above materials. We present here the FMR analysis of Fe$\sub$82/Mn$\sub$8-x/B$\sub$x/Zr$\sub$10/ alloy near the Curie point.

• 한국자기학회지
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• 제5권5호
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• pp.841-845
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• 1995

The effect of small addition of Nb on the electrical resistivity and Hall coeffcient of the amorphous $Fe_{83}Zr_{7}B_{10}$ alloy and annealed ones ones below the crystallization temperature were investigated, which has been considered to be suitable for high frequency core material. At room temperature, their resistivities $\rho$ and the spontaneous Hall coeffcients $R_{s}$ are $~1.6\;{\mu}{\Omega}m$ and $~3{\times}10^{-8}m^{3}/As$, respectively. $R_{s}$ and $\rho$ are decreased with increasing temperature from 100 K to room temperature. Side-jump effect was adopted to analyze the effect of the small variation of conentration and annealing. The quantity of $R_{s}/{\rho}^{2}$ at room temperature, which is directly related to the electronic structure of the mother alloy, remained almost a constant except as quenched one as it can be predicted from the side-jump effect. The unexpected temperature dependence of $R_{s}/{\rho}^{2}$ measured at low fields much below Tc is left as a question.

• 대한금속재료학회지
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• 제46권8호
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• pp.524-537
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• 2008

Zr-based amorphous alloy matrix composites reinforced with metallic continuous fibers were fabricated by liquid pressing process, and their fracture properties were investigated by directly observing microfracture process using an in situ loading stage installed inside a scanning electron microscope chamber. About 60 vol.% of metallic fibers were homogeneously distributed inside the amorphous matrix. Apparent fracture toughness of the stainless-steel- and tungsten-fiber-reinforced composites was lower than that of monolithic amorphous alloy, while that of the Ta-fiber-reinforced composite was higher. According to the microfracture observation, shear bands or cracks were initiated at the amorphous matrix, and the propagation of the initiated shear bands or cracks was effectively blocked by fibers, thereby resulting in stable crack growth which could be confirmed by the fracture resistance curve (R-curve) behavior. This increase in fracture resistance with increasing crack length improved fracture properties of the fiber-reinforced composites, and could be explained by mechanisms of formation of multiple shear bands or multiple cracks at the amorphous matrix and blocking of crack or shear band propagation and multiple necking at metallic fibers.

• 한국분말재료학회지
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• 제11권3호
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• pp.193-201
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• 2004

1960년 Au-Si계 합금에서 처음으로 비정질상이 급속 응고법에 의해 보고된 이래/sup 1)/ 지난 40년 간 많은 합금계에서 비정질상이 보고되어졌다. 대표적으로 Fe-, Ni-, Co기 합금 등 많은 합금계에서 비정질상이 보고되었으나, 비정질상의 형성을 위해서는 약 105 K/s이상의 높은 냉각속도를 필요로 하였다. 1980년대 수백 K/s의 낮은 냉각속도 하에서도 비정질상이 형성될 수 있는 다원계 합금(multi-component alloy)이 Mg-Ln-(Ni, Cu, Zn), Ln-Al-TM 합금에서 보고되어 졌으나 많은 관심을 받지 못하다가 1993년 Zr-Ti-Ni-Cu-Be 합금에서 수 ㎝ 크기의 비정질합금 제조가 보고되면서 전 세계적으로 많은 관심을 받게 되었다. Zr-Ti-Ni-Cu-Be계 벌크 비정질 합금이 보고된 후 Zr-(Nb,Pd)-Al-TM, Pd-Cu-Ni-P, Fe-Co-Zr-Mo-W-B, Ti-Zr-Ni-Cu-Sn등 여러 합금계에서 벌크 비정질 합금이 보고되었다. (중략)

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.111-111
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• 2016

Two step PEO ceramic coatings were formed on AZ91 magnesium alloy in $ZrO_2$ nanoparticles and $K_2ZrF_6$ based colloidal electrolyte solution for various voltages. Surface and layers tructure of the coatings was analyzed using SEM (ScanningElectronMicroscope). Structure analysis revealed that surface of the coating was transferred from individual pancake or craters-based structure to cluster-based structure with increasing the voltage of the secondary step process. Further, it was confirmed that the cluster zone was richin Zr-based complexes and formed due to high intensives parks. Increase in the Zr contents as discovered from the EDS analysis confirmed the rise in amorphous form of the Zr-based species, which justified the results of XRD where no increase in the intensity of Zr-based species was observed with increase in voltage. Potentiodynamic polarizariotion and impedance spectroscopy techniques were used to evaluate the corrosion performance of the coatings. The highest corrosion resistance was found for coatings prepared at 240V. The same specimen was found having highest and uniform vickers hardness ~1070.5 HV. The superior mechanical and electrochemical properties of the said coating can be attributed to the defect-less microstructure and the optimal role of $ZrO_2$ nanoparticles in the secondary PEO process at 240V.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.417-420
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• 2006

The composition and structure of dendrite phase within $Zr_{76.11}Ti_{4.20}Cu_{4.51}Ni_{3.16}Be_{1.49}Nb_{10.53}$ bulk metallic glass (BMG) were confirmed by using an EPMA, XRD and TEM, respectively. The chief elements of dendrite phase were Zr-Ti-Nb and had a BCC structure. The thermal properties of this BMG have been then subsequently investigated by using a differential scanning calorimeter (DSC). The glass transition and crystallization onset temperatures were determined as $339.7^{\circ}C$ and $375.8^{\circ}C$ for this alloy, respectively. Mechanical properties have also been examined by conducting a series of uniaxial compression tests at various temperatures within supercooled liquid region under the strain rates between $10^{-4}/s$ and $3{\times}10^{-2}/s$. The deformation behavior of BMG composite within supercooled liquid region is similar to one of Vit-1 exhibiting amorphous single phase alloy. The flow stresses of BMG composite, however, are entirely higher than those of Vit-1 because dendrite phases are interfere with moving of atoms.

• 한국재료학회지
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• 제15권4호
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• pp.281-284
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• 2005

Room and high temperature deformation behaviors of Cu-Zr-Ti-Pd bulk metallic glasses produced by copper mold casting were investigated. The addition of Pd was shown to enhance the glass forming ability and thermal stability of Cu-Zr-Ti base bulk metallic glass. The compressive strength of $Cu_{55}Zr_{30}Ti_{10}Pd_5$ bulk metallic glass was 2230 MPa with 1.8 plastic strain. The stress overshoot and yield drop phenomenon were observed below $487^{\circ}C$ and a drastic decrease in the flow stress was observed at $487^{\circ}C$. The stress overshoot is thought to be associated with stress-induced structural relaxation.

• 한국자기학회지
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• 제10권2호
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• pp.54-61
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• 2000

마그네트론 스퍼터를 사용하여 증착한 CoNbZr 합금박막의 제조 조건 및 열처리에 따르는 구조 및 자기적 성질의 변화를 연구하였다. Ar분압 2mTorr, RF 인가전력 130 W에서 증착되어진 $Co_{87.0}$N $b_{8.5}$Z $r_{4.5}$막은 최대 비저항 3000 $\mu$Ω.cm을 나타냄으로써 가장 안정한 비정질상을 형성하였으며 100 MHz에서 1095의 최대투자율, 1.75 Oe의 최소 보자력을 나타내었다. Ar 분압이 2 mTorr 이상으로 증가할 경우 그리고 RF 인가전력이 130 W 이상으로 증가할 경우 주상정 구조의 발달과 불안정한 비정질상의 형성으로 투자율은 감소하고 보자력은 증가하는 것을 확인하였다 1 mTorr에서 증착되어진 막과 190 W에서 증착되어진 막은 결정질 상을 형성하여 100 이하의 낮은 투자율과 60 Oe의 높은 보자력을 나타내었다. 회전자장중 열처리에 의해 이방성을 제어할 수 있음을 확인하였으며, 증착상태에서 보였던 1095의 투자율은 1345로 증가하였다.증가하였다.