• 열처리공학회지
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• 제5권3호
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• pp.149-156
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• 1992

Transformation behavior and reversible shape memory effct of Ti-Ni-Cu alloys with various Cu content has been investigated by means of electrical resistivity measurement, differential scanning calorimetry. X-ray diffraction and strain gage sensor. The transformation sequence in Ti-Ni-Cu alloys substituted by Cu for Ni up to 5at.% occurs to $B2{\leftrightarrow}B19^{\prime}$ and it proceeds in two stages by addition of 10 at.%Cu. i.e. $B2{\leftrightarrow}B19{\leftrightarrow}B19^{\prime}$. But the content of Cu increases up to 20at.%, it has been transformed in one stage ; $B2{\leftrightarrow}B19$. The shape change of Ti-40Ni-10Cu alloy which was constrain aged in circular form bended in $B2{\leftrightarrow}B19$ transformation but it spreaded out in $B19{\leftrightarrow}B19^{\prime}$ transformation. The amount of reversible shape change (${\Delta}{\varepsilon}$) of Ti-47Ni-3Cu alloy constrain aged at $400^{\circ}C$ after solution treatment has a maximum value of about $5.6{\times}10^{-3}$, but that of cold rolled and constrain aged specimens exhibits a little value independent of Cu concentrations.

• 한국재료학회지
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• 제29권4호
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• pp.258-263
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• 2019

Since the directly bonded interface between TiAl alloy and SCM440 includes lots of cracks and generated intermetallic compounds(IMCs) such as TiC, FeTi, and $Fe_2Ti$, the interfacial strength can be significantly reduced. Therefore, in this study, Cu is selected as an insert metal to improve the lower tensile strength of the joint between TiAl alloy and SCM440 during friction welding. As a result, newly formed IMCs, such as $Cu_2TiAl$, CuTiAl, and $TiCu_2$, are found at the interface between TiAl alloy and Cu layer and the thickness of IMCs layers is found to vary with friction time. In addition, to determine the relationship between the thickness of the IMCs and the strength of the welded interfaces, a tensile test was performed using sub-size specimens obtained from the center to the peripheral region of the friction-welded interface. The results are discussed in terms of changes in the IMCs and the underlying deformation mechanism. Finally, it is found that the friction welding process needs to be idealized because IMCs generated between TiAl alloy and Cu act to not only increase the bonding strength but also form an easy path of fracture propagation.

• 한국재료학회지
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• 제11권3호
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• pp.215-220
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• 2001

본 실험에서는 반응성 스퍼터링법으로 $N_2$/Ar 유속비를 달리하여 약 200 과 650 두께의 비정질 Ti-Si-N막을 증착한 후 Cu (750 )와 Si사이의 barrier 특성을 면저항측정, XRD, SEM, RBS 그리고 Ti-Si-N막에서 질소 함량의 영향에 초점을 둔 ABS depth profiling 등의 분석방법을 통해 조사되었다. 질소 함량이 증가함에 따라 처음에는 불량 온도가 46%까지 증가하다가 그 이상에서는 감소하는 경향을 보였다. 650 의 Ti-Si-N barrier막을 80$0^{\circ}C$에서 열처리 후에는 Cu$_3$Si 피크만 관찰될 뿐 Cu피크는 거의 완전히 사라졌으므로 Barrier 불량기구는 Cu$_3$Si상을 형성하기 위해 Si 기판내로의 Cu의 확산에 의해 일어난 것으로 보인다. 본 실험에서 Ti-Si-N의 최적 조성은 $Ti_{29}$Si$_{25}$N$_{46}$이었다. 200 과 650 두께의 $Ti_{29}$Si$_{25}$N$_{46}$ barrier 층의 불량온도는 각각 $650^{\circ}C$와 $700^{\circ}C$이었다.이었다.

• Journal of Welding and Joining
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• 제14권1호
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• pp.47-56
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• 1996

The purpose of this study is to develope an insert metal which can be brazed at lower temperature than the conventionally used insert metal and provide higher strength joint than base metal. In the review of binary phase diagram concerning Ti, Cu and Ni resulted in the discovery of Si having eutectic composition with them. The microstructure and the distribution of elements in reaction zone between CP Ti and insert metal were investigated by Optical Microscopy, SEM/EDX, EPMA, X-RAY. The newly developed insert metal is Ti-15wt%Cu-18wt%Ni-2wt%Si, which can yield the lower brazing temperature(1183K) compared with the conventional Ti-Cu-Ni system insert metal. The joints with this insert metal had tensile strength of 385MPa in the bonding temperature range of 1183K to 1243K.

• 한국표면공학회지
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• 제42권5호
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• pp.246-249
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• 2009

Cu-Ti alloys with titanium in the range of 0.5-6.0 wt% were developed to evaluate the effect of the titanium content and heat treatment on microstructure, hardness, and electrical conductivity. The hardness of the Ti-added copper alloys generally increased with the increase in titanium content and hardening was effective up to the 2.5 wt%-Ti addition. Microstructural examination showed that the second phase of $Cu_4Ti$ started to precipitate out from the 3.0 wt% Ti-addition, and the precipitate size and volume fraction increased with further Ti addition. Aging of the present Cu-Ti alloys at $450^{\circ}C$ for 1 h increased the hardness; however, the further aging up to 10 h did not much change the hardness. In the present study, it was inferred that in optimal Ti addition and aging condition Cu-Ti alloy could have the hardness and electrical conductivity values which are comparable to those of commercial Cu-Be alloy.

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.432-437
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• 2013

고분자 전해질 연료전지 구동 시 양극 활성 물질에 대한 CO 피독을 방지하기 위해 Cu를 촉매 활성 종으로 사용하고 반응물의 확산이 용이한 몇 가지 메조 세공 물질을 지지체로 이용하여 CO 선택적 산화 반응(PROX반응)을 실시하였다. 그 결과 거대 세공을 가진 SBA-15를 지지체로 사용했을 때 우수한 CO 산화 활성을 보였으며 특히 Cu 담지 량에 비례하여 활성은 증가하였다. 또한 Cu의 분산도를 높이고자 첨가한 Ti 성분은 저온에서 CO 산화 성능을 높이는데 기여하였다. 특히 Ti 성분을 20 wt-% 첨가한 Cu/Ti20-SBA-15 촉매에서 Cu의 분산도가 가장 우수하였으며 CO 산화활성 역시 개선됨을 확인하였다.

• 한국재료학회지
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• 제10권7호
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• pp.482-488
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• 2000

(hfac) Cu(1,5-COD)(1,1,1,5,5,5-hexafluro-2,4-pentadionato Cu(I) 1,5-cyclooctadine) 증착원을 이용하여 MOCVD(metal organic chemical vapor deposition)로 Cu 박막을 형성시키고, MOCVD에 의한 TiN 기판 변화가 Cu 증착에 미치는 영향을 조사하였다. 공기 중에 노출시킨 기판은 MOCVD 에 의한 Cu 핵생성 및 초기성장에 영향을 미쳐 입자크기가 작고, 입자간의 연결성이 떨어졌으며, in-situ MOCVD Cu의 경우는 입자크기가 크고, 입자간의 연결성이 우수하여 1900$\AA$ 이상의 두께에서는 $2.0{\mu}{\Omega}-cm$ 정도의 낮은 비저항을 유지하였다. 또한 접착력에서는 in-situ MOCVD TiN 의 경우가 보다 우수하였다. 이와 같은 결과를 토대로 MOCVD Cu 성장단계를 제시하였다.

• 한국재료학회지
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• 제15권5호
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• pp.318-322
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• 2005

Ti-capped NiSi contacts were formed on $p^+/n$ junctions to improve the leakage problem and then Cu was deposited without removing the Ti-capping layer in an attempt to utilize as a diffusion barrier. The electrical characteristics of these $p^+/n$ diodes with Cu/Ti/NiSi electrodes were measured as a function of drive-in RTA(rapid-thermal annealing) and silicidation temperature and time. When drive-in annealed at $900^{\circ}C$, 10 sec. and silicided at $500^{\circ}C$, 100 sec., the diodes showed the most excellent I-V characteristics. Especially, the leakage current was $10^{-10}A$, much lower than reported data for diodes with NiSi contacts. However, when the $p^+/n$ diodes with Cu/Ti/NiSi contacts were furnace-annealed at $400^{\circ}C$ for 40 min., the leakage current increased by 4 orders. The FESEM and AES analysis revealed that the Ti-capping layer effectively prohibited the Cu diffusion, but was ineffective against the NiSi dissociation and consequent Ni diffusion.

• 한국재료학회지
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• 제16권8호
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• pp.511-515
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• 2006

The dispersion hardened $Cu-TiB_2$ composites are a promising candidate for applications as electrical contact materials. The $Cu-TiB_2$ composites for electrical contact materials can reduce material cost and resource consumption caused by wear, due to their good mechanical and electrical properties. In this study, we investigated the wear phenomenon for $Cu-TiB_2$ composites fabricated with hot extrusion, by varying particle sizes and volume fractions of $TiB_2$. The wear tests were performed under the dry sliding condition with a fixed total sliding distance of 40 m. The contact loads at a constant speed of 3.5 Hz were 20, 40, 60, and 80 N. The friction coefficients and wear losses were measured during wear tests. Worn surfaces and wear debris after wear tests were investigated using the scanning electron microscope and the optical microscope. The microstructures of interface between Cu matrix and $TiB_2$ particle before and after wear tests were studied by the transmission electron microscope.

• 한국재료학회지
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• 제14권1호
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• pp.73-77
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• 2004

The mechanical and electrical properties of $Cu-TiB_2$ composites prepared by hot extrusion and cold drawing according to the variation of $TiB_2$ contents and the size of $TiB_2$ particle have been studied. The experimental results showed that the electrical conductivity was decreased with increasing the $TiB_2$ content, and their tensile strength and hardness increased inversely. In the case of the same content of $TiB_2$ particle, the smaller $TiB_2$ particle, the higher their mechanical properties. The electrical conductivity of $Cu-TiB_2$ composites showed more than 70%IACS. Their yield strength and hardness were more than 120 MPa and HRB 60～70, respectively.