• 한국자기학회지
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• 제7권1호
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• pp.31-37
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• 1997

조성과 강자성 상하지층이 Co-Ag 나노입상 합금박막의 거대자기저항과 포화자기장에 미치는 효과에 대하여 연구하였다. 두께 3000 .angs. , 30 at.% Co 조성의 증착된 상태의 합금박막에서 23 %의 최대 자기저항비를 얻었으며 포화자기장은 2.3 kOe 였다. 두께 .angs.의 $Co_{30}$Ag$_{70}$ 합금박막의 자기저항비는 3.65 %, 포화자기장은 3.0 kOe 이었으며 200 .angs. 의 Fe를 상하지층으로 증착하였을 때 자기저항비는 3.3%, 포화자기장은 1.23 kOe로 감소하였다. 강자성 상하지층이 교환결합에 의하여 합금박막의 포화자기장을 감소 시키는 효과가 있었으며 그 효과는 합금박막의 두께가 약 3000 .angs. 이하에서 나타났다. 교환결합 강자성체 인 Co, NiFe, 그리고 Fe중에서 포화자 기장 감소에 가장 효과적인 재료는 Fe 이었다.다.

• 대한치과보철학회지
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• 제27권1호
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• pp.49-54
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• 1989

The purpose of this study was to investigate the interfacial elemental change when solding the Ni-Co-Cr dental removable partial denture alloy and Fe-Cr-Ni wrought wire alloy with Ag-Cu-Zu Silver solder, by EDXA, EPMA, to investigate the appropriateness of clinical usefullness for repair the fractured clasps of removable partial dentive. The result of this study was as follows: 1. The Ni element of major component of Ticonium penetrate into the silver solder 2. The movement Age element of silver solder into Fe-Cr-Ni wire was not significant, by EDXA and EPMA.

• 한국자기학회지
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• 제7권6호
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• pp.308-313
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• 1997

조성과 강자성 상하지층이 CoFe-Ag 나노입상 합금박막의 거대자기저항과 포화자기장에 미치는 효과에 대하여 연구하였다. 3000 .angs. 두께의 ( $Co_{92}$Fe$_{8}$)$_{31}$Ag$_{69}$ 합금박막에서 최대 자기저항 25.7%를 얻었고, 그 때 포화자장은 2.1 kOe 이었다. 100 .angs. 두께의 박막은 자기저항비가 1.2%이고 포화자장은 5.2 kOe 이었다. 200 .angs. 두께의 합금 박막에 100 .angs. Fe를 상하지층으로 증착하였을 때 자기저항은 9.5 %dptj 11 %로 증가하였고 포화자기장은 2.8 kOe에서 1.8 kOe로 개선되었다. 300 .angs. 이하의 합금박막에 강자성 상하지층의 피복은 교환결합에 의하여 합금박막의 포화자기장을 감소시키는 효과가 있었다. 강자성 상하지층에 의한 자기저항의 증가는 표면에서의 전도전자의 스핀 전도산란의 감소와 계면저항에 의한 전류새흐름의 감소로 기인되는 것으로 보인다. 자기저항의 증가 효과는 합금박막의 두께가 약 300 .angs. 이하에서 나타났다. 교환결합 강자성체인 NiFe 그리고 Fe 중에서 Fe가 교환결합에 의한 포화자기장 감소에 좀더 효과적이었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.355-356
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• 2009

The change of thermal expansion and mechanical behaviors by cold working has been investigated in Fe-29%Ni-17%Co low thermal expansion Kovar alloy. Fe-29%Ni-17%Co alloy was cold rolled gradually and prepared to plates having reduction ratio of 0%, 20%, 40%, 60%, and 80%. Annealing effect on the properties was also studied. Thermal expansion was measured from $25^{\circ}C$ to $600^{\circ}C$ with a heating rate of $5^{\circ}C$/min by using vacuum differential dilatometer. It was found that thermal expansion coefficient ($\alpha_{30{\sim}400}$) slightly decreased (reduction ration of 20%) and then remarkably increased (above reduction ration of 40%) with increasing reduction ratio of cold rolling. Thermal expansion coefficient ($\alpha_{30{\sim}400}$) was sharply decreased after annealing heat-treatment. Yield and tensile strengths were continuously increased and elongation was decreased by cold roiling. Microstructural observation and X-ray diffraction analysis results showed that the $\alpha$ phase significantly increased as the reduction ratio increased. The slight decrease of thermal expansion coefficient bellow reduction ration of 20% could be explained by the destroying short-range ordering and the decreasing of grain size. The significant increase of thermal expansion coefficient with cold rolling mainly attributed to the appearance of $\alpha$ phase. The correlation between the microstructural cause and invar phenomena for the low thermal expansion behavior was also discussed.

• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.308-317
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• 2007

We fabricated thermally-evaporated 10 nm-Ni/(poly)Si and 10 nm-$Ni_{0.5}Co_{0.5}$/(Poly)Si structures to investigate the microstructure of nickel silicides at the elevated temperatures required lot annealing. Silicides underwent rapid annealing at the temperatures of $600{\sim}1100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to investigate the sheet resistances. A transmission electron microscope and an Auger depth profilescope were employed for the determination of vortical microstructure and thickness. Nickel silicides with cobalt on single crystal silicon actives and polycrystalline silicon gates showed low resistance up to $1100^{\circ}C$ and $900^{\circ}C$, respectively, while the conventional nickle monosilicide showed low resistance below $700^{\circ}C$. Through TEM analysis, we confirmed that a uniform, $10{\sim}15 nm$-thick silicide layer formed on the single-crystal silicon substrate for the Co-alloyed case while a non-uniform, agglomerated layer was observed for the conventional nickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicide showed a unique silicon-silicide mixing at the high silicidation temperature of $1000^{\circ}C$. Auger depth profile analysis also supports the presence of this mixed microstructure. Our result implies that our newly proposed NiCo-alloy composite silicide process may widen the thermal process window for the salicide process and be suitable for nano-thick silicides.

• 한국분말재료학회지
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• 제26권2호
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• pp.107-111
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• 2019

The activation energy to create a phase transformation or for the reaction to move to the next stage in the milling process can be calculated from the slop of the DSC plot, obtained at the various heating rates for mechanically activated Al-Ni alloy systems by using Kissinger's equation. The mechanically activated material has been called "the driven material" as it creates new phases or intermetallic compounds of AlNi in Al-Ni alloy systems. The reaction time for phase transformation by milling can be calculated using the activation energy obtained from the above mentioned method and from the real required energy. The real required energy (activation energy) could be calculated by subtracting the loss energy from the total input energy (calculated input energy from electric motor). The loss energy and real required energy divided by the reaction time are considered the "metabolic energy" and "the effective input energy", respectively. The milling time for phase transformation at other Al-Co alloy systems from the calculated data of Al-Ni systems can be predicted accordingly.

• 한국분말재료학회지
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• 제25권3호
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• pp.208-212
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• 2018

In this paper, a new $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ high entropy alloy (HEA) is identified as a strong candidate for the single face-centered cubic (FCC) structure screened using the upgraded TCFE2000 thermodynamic CALPHAD database. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA is fabricated using the mechanical (MA) procedure and pressure-less sintering method. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA, which consists of elements with a large difference in melting point and atomic size, is successfully fabricated using powder metallurgy techniques. The MA behavior, microstructure, and mechanical properties of the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA are systematically studied to understand the MA behavior and develop advanced techniques for fabricating HEA products. After MA, a single FCC phase is found. After sintering at $900^{\circ}C$, the microstructure has an FCC single phase with an average grain size of $18{\mu}m$. Finally, the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA has a compressive yield strength of 302 MPa.

• 동력기계공학회지
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• 제18권4호
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• pp.72-77
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• 2014

The aim of this study to investigate polarization characteristics of WC-based alloy coatings fabricated by high velocity oxygen fuel(HVOF) process. The coatings were fabricated by HVOF process with WC-CrC-Ni, WC-Co-Cr, WC-Co composite powders. Corrosion tests were carried out using potentiostat/galvanostat at solution with pH 2 and pH 6. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be analyzed from polarization curve. WC-Co-Cr coating showed more incorrodible characteristics than other coatings at solution pH 2. WC-CrC-Ni coating was more favorable anti-corrosion characteristics than other coatings at solution with pH 6.

• Journal of Welding and Joining
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• 제19권5호
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• pp.540-547
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• 2001

This study has evaluated the wear behavior of PTA (Plasma Transferred Arc) Inconel 625 and Stellite 6 overlays on Nimonic 80A substrate. Nimonic 80A alloy was also included for comparison. In order to evaluate the wear performance, three-body abrasive wear test and pin-on-disk dry sliding wear test were performed. Microstructural development during the solidification of deposits is also discussed. Wear test results show that the wear rate of Stellite 6 deposit is lower than that of Inconel 625 deposit and Nimonic 80A. The sliding wear resistance of overlay deposits follows a similar trend to the abrasive wear resistance, but for Nimonic 80A. The main wear mechanisms were abrasive wear for Inconel 625 deposit, adhesive wear and delamination for Stellite 6 deposit in pin-on-disk dry sliding wear test and ploughing in three-body abrasive wear test. Cross sectional examinations of the worn surface of pin specimens after pin-on-disk dry sliding wear test implies that the plastic deformation near worn surface has occurred during the wear testing.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1138-1139
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• 2006

The present study has shown that the effect of boron and phosphorus in Ni-Cr-Si-X alloy to interfacial reactions and bonding strength of diamond-steel substrate, and the influence of various construction parameters on the formation of the topography of the tool. And these factors are required to making a good brazed tool. The microstructures and phase change of the brazed region were analyzed into SEM, EDS. According to the electron probe microanalysis, while brazing, the chromium present in the brazing alloy segregated preferentially to the surface of the diamond to form a chromium rich reaction product, which was readily wetted by the alloy.