• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.109-110
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• 2006

We have studied the effect of C/Ti atomic ratio of TiCx (x=0.5, 0.75 and 1.0) raw powder on the properties of the Ti-Mo-WTiC sintered hard alloy. The decrease of C/Ti atomic ratio accelerated the densification in the sintering process. The hardness was remarkably improved up to 1350HV with decreasing the C/Ti atomic ratio because of increase of TiCx phase volume content and its fine dispersion. From the results of electro-chemical tests in acid and 3% NaCl solutions, it was obvious that every alloy had excellent corrosion resistance, which meant about 200 times better than that of WC-Co cemented carbide.

• 한국항행학회논문지
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• 제7권2호
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• pp.211-216
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• 2003

본 논문에서는 오래 전부터 NMOS의 게이트 전극으로 사용된 폴리실리콘을 대체할 수 있는 Ta-Ti 합금의 특성에 대해 연구하였다. 실리콘 기판 위에 열적으로 성장된 $SiO_2$ 위에 Ta과 Ti의 두 타깃을 사용하여 co-sputterring 방법으로 Ta-Ti 합금을 증착하였다. 각각의 타깃은 100W의 sputtering power로 증착하여 시편을 제작하였다. 또한 비교 분석을 위하여 Ta을 100W의 sputtering power로 증착한 시편도 제작하였다. 제작된 Ta-Ti 합금 게이트의 열적/화학적 안정성을 검토하기 위하여 $600^{\circ}C$에서 급속열처리를 수행한 결과 소자의 성능 저하는 나타나지 않았다. 또한 전기적 특성 분석 결과 Ta-Ti 합금은 NMOS에 적합한 일함수인 4.13eV를 산출해 낼 수 있었고, 면저항 역시 폴리실리콘에 비해 낮은 값을 얻을 수 있었다.

• 한국분말재료학회지
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• 제27권1호
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• pp.52-57
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• 2020

In this study, we report the microstructure and characterization of Ta₂₀Nb₂₀V₂₀W₂₀Ti₂₀ high-entropy alloy powders and sintered samples. The effects of milling time on the microstructure and mechanical properties were investigated in detail. Microstructure and structural characterization were performed by scanning electron microscopy and X-ray diffraction. The mechanical properties of the sintered samples were analyzed through a compressive test at room temperature with a strain rate of 1 × 10^-4 s^-1. The microstructure of sintered Ta₂₀Nb₂₀V₂₀W₂₀Ti₂₀ high-entropy alloy is composed of a BCC phase and a TiO phase. A better combination of compressive strength and strain was achieved by using prealloyed Ta₂₀Nb₂₀V₂₀W₂₀Ti₂₀ powder with low oxygen content. The results suggest that the oxide formed during the sintering process affects the mechanical properties of Ta₂₀Nb₂₀V₂₀W₂₀Ti₂₀ high-entropy alloys, which are related to the interfacial stability between the BCC matrix and TiO phase.

• 화약ㆍ발파
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• 제19권1호
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• pp.101-110
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• 2001

Depleted uranium (DU) outperforms tungsten heavy alloys (WHA) by about 10%. Because of environmental and hence, political concerns, there is a need to improve WHA performance, in order to replace the DU penetrators. A technique of metal powder compaction by the detonation of an explosive has been applied to tungsten-titanium(W-Ti) powder materials that otherwise may be difficult to fabricate conventionally or have dissimilar, nonequilibrium, or unique me1astab1e substructures. However, the engineering properties of compacted materials are not widely reported and are little known especially for the "unique" composition of W-Ti alloy. To develop high-performance tungsten composites with superior ballistic attributes, it is necessary to understand, carefully document controlled experimental results, and develop basic computational models for potential composites with controlled microstructures. A detailed understanding and engineering application of W-Ti alloy can lead to the development of new structural design for engineering components and materials.

• 연구논문집
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• 통권29호
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• pp.163-171
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• 1999

A new titanium alloy system. Ti-xFe-ySi (x,y=0-4 wt%). was designed and characterized with the point at low cost and high strength for casting applications. Fe improved room and elevated temperature mechanical properties owing to solid solution hardening and beta phase stabilization. Si yielded titanium silicides and Si addition over 1 wt% resulted in poor ductility due to coarse silicide chains at prior beta boundaries. The optimum composition was found to be Ti-4Fe-(0.5-1)Si in the viewpoint of tensile strength and ductility which are comparable to the Ti-6Al-4V. The metal-mould reaction was also examined for Ti-xFe and Ti-xSi binary alloy system. The thickness of surface reaction layer w as not affected significantly with Fe content, while it was decreased with Si content. In the Ti-4Si alloy, no reaction layer was found. The depth of surface hardening layer was about $200\mum$ regardless of the mould materials.

• 한국결정성장학회지
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• 제11권4호
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• pp.133-137
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• 2001

고출력 이산화탄소 레이저빔에 의한 TiC/Al 표면합금의 특성을 연구하였다. 이 과정을 분석하기 위해 기본금속[Al]과 TiC 분말입자 사이의 물리적 특성을 측정하였다. 표면층의 크기와 모양, 광학적 흡수율 그리고 분말효율을 TiC/Al 행력에서 레이저출력의 함수로 측정하였다. TiC 분말을 사용한 경우와 사용하지 않은 경우의 기본금속내의 흡수율은 레이저 출력이 증하가면 감소하였다. 레이저출력이 2kW에서 4.5kW 범위로 증가되면 분말효율은 4%에서 12%까지 증가하였다. 그러나 TiC 분말입자는 용융된 알루미늄에는 용해되지 않는다. 이 결과 분말입자가 증가되면 쉽게 표면층을 투과하여 금속행렬속에 2개의 위상상태로 생성된다.

• 열처리공학회지
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• 제32권5호
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• pp.195-200
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• 2019

For expanding the applications and workability of TiAl alloy, elongation is very important property. Fine microstructure is needed for elongation and physical properties of TiAl alloys. In this study, The effects of cyclic heat treatment process for fine microstructure of Ti-46Al-Nb-W-Cr-Si-C alloy, which was made by VAR (vacuum arc remelting) and VIM(vacuum induction melting) centrifugal casting process, was investigated. Cycle heat treatment process was very effective for recrystallization of this TiAl system, which has microstructure size of $50{\sim}100{\mu}m$ through pre-heat treatment, cyclic heat treatment in ${\alpha}+{\gamma}$ phase region and solution heat treatment respectively. Refined grain size was finally confirmed by photos of optical microscope and scanning electron microscope.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1165-1167
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• 1995

The Cu-Si alloy has been proposed as a new matrix materal for filamentary Nb-Ti wires in AC use. The Cu-Si alloy shows approprite mechanical and electrical properties, and is economically more favourable than the Cu-Ni alloy matrix used currently. Moreover, the addition of Si to Cu prevents the formation of intermetallic compounds around the filaments. After we investigated resistivity and hardness of Cu-Si alloy as matrix materal, investigated CuSi/NbTi interface reactions and superconductivities of superconducting wires that were made by various heat treatment.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1157-1158
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• 2006

Internally nitrided dilute W-Ti alloy specimens having a heavily deformed surface microstructure were prepared by a multi-step internal nitriding at 1573-2073 K. Primary nitriding below their recrystallization temperature induced a precipitation of ultrafine TiN particles. After secondary and tertiary nitriding, those precipitates grew into rod-like TiN with a length of 20-60 nm. The recrystallization temperature after nitriding was elevated above 2073 K. The yield strength at 1773 K obtained from nitrided W-0.5 mass% Ti alloy was about 5 times as large as that of the recrystallized specimen. DBTT of the nitrided alloys was about 373 K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.375-377
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• 1998

The magneto-optical properties of Co/Co$_2$TiSn two-phase magnet films were studied. These films show that relatively large Kerr rotations which are -0.4 deg. at the wavelength of 400 nm, compared to that of pure Co. It is conceivable that the magneto-optical effects may be due to both contributions of ferromagnetic Co matrix and ferromagnetic Co$_2$TiSn Heusler alloy precipitate. The perpendicular magnetization curve domonstrates a typical bubble domain hysteresis loop. the saturation magnetization change of the annealed film is less sensitive to temperature in the low temperature region and the Curie temperature of Co$_2$TiSn Heusler alloy precipitate is a little higher in the annealed film. These can be explained by the increase of the number of Co-Co exchange interaction in Heusler alloy structure resulting from the change of chemical ordering by annealing.