• Title, Summary, Keyword: TiAl

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Elevated Temperature Compressive Properties of Al-Ti Alloys Prepared by Mechanical Alloying (기계적 합금화에 의해 제조된 AS-Ti합금의 고온압축성질)

  • 이광민
    • Journal of Korean Powder Metallurgy Institute
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    • v.5 no.2
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    • pp.129-132
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    • 1998
  • The elevated temperature compressive tests were carried out in order to investigate the deformation behavior and microstructural characteristics of Al-8%Ti, Al-12%Ti and Al-16%Ti (wt%) alloys, which were mechanically alloyed and consolidated by vacuum hot pressing, A13Ti intermetallic phases were formed with sizes of few hundred nanometers in the mechanically alloyed Al-Ti alloys. The compressive strength of mechanically alloyed AA-Ti alloys increased with decroasing the temperature and with increasing the strain rate. The strain rate sensitivities of Al-8%Ti, Al-12%Ti and Al-16%Ti alloys were measured 0.02,0.03, and 0.14, respectively, at 35$0^{\circ}C$.

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Al-10wt%Ti-4wt%F Alloys as In-situ Composites through Rapid Solidification(II) (급냉응고법에 의한 In-Situ 복합재료로서의 Al-10wt%Ti-4wt%Fe 합금 (II))

  • Kim, Hye-Seong;Jeong, Jae-Pil;Gwon, Suk-In;Geum, Dong-Hwa
    • Korean Journal of Materials Research
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    • v.8 no.12
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    • pp.1127-1132
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    • 1998
  • The possibilities of producing Al-10%Ti-4%Fe composites through in-situ processing and thus achieving mechanical property improvements over binary Al-10%Ti to a level or higher exhibited by PM SiC/A12124 composites were explored in this study. The microstructure of in-situ processed Al-10%Ti-4%Fe composites was similar to that of Al matrix composites reinforced with discontinuous SiC particulates(SiC/A12124) and significant enhancements in elastic modulus, tensile strength and wear resistance were observed as compared to Al-10%Ti alloy. These results can be attributed to the in-situ formed Al. Fe by third element addition, leading to additional dispersion strengthening effect over $Al_3Ti$ phase reinforcement in Al-Ti system.

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Corrosion of Ti3AlC2 at 800-1100℃ in SO2 gas atmosphere (Ti3AlC2의 800-1100℃, SO2 가스 분위기에서의 부식)

  • Won, Seong-Bin;Chunyu, Xu;Hwang, Yeon-Sang;Lee, Dong-Bok
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.114-115
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    • 2013
  • $Ti_3AlC_2$ was corroded between 800 and $1100^{\circ}C$ in an Ar-0.2% $SO_2$ gas atmosphere according to the equation: $Ti_3AlC_2+O_2{\rightarrow}rutile-TiO_2+{\alpha}-Al_2O_3$ + (CO or $CO_2$). The scales that formed on the $Ti_3AlC_2$ were thin and rich in ${\alpha}-Al_2O_3$, whose growth rate was exceedingly slow. The $TiO_2$ was present either as the outermost surface scale or a mixture inside the ${\alpha}-Al_2O_3$-rich scale. In the $Ti_3AlC_2$, the activity and diffusivity of Ti were low, whereas those of Al were high. This was the main reason for the superior corrosion resistance of $Ti_3AlC_2$ over TiAl.

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Crack propagation behavior of in-situ structural gradient Ni/Ni-aluminide//Ti/Ti-aluminide laminate materials (Ni/Ni-aluminide//Ti/Ti-aluminide 구조경사형 층상재료의 균열 전파 거동)

  • Chung, D.S.;Kim, J.K.;Cho, H.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.6
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    • pp.269-275
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    • 2005
  • Ni/Ni-aluminide/Ti/Ti-aluminide laminate composite, considered as a functionally gradient material, was manufactured by thin foil hot press technique. Thick intermetallic layers of NiAl and $TiAl_3$ were formed by a self-propagating high-temperature synthesis (SHS) reaction, and thin continuous taters of $Ni_3Al$ and TiAl were formed by a solid-state diffusion. Fracture resistance with loading along the crack arrester direction is higher than crack divider direction due to the interruption of crack growth in metal layers. The $Ni_3Al$ and NiAl intermetallic layer showed cleavage and intergranular fracture behavior, respectively, while the fracture mode of $TiAl_3$ layer was found to be an intragranular cleavage. The debonding between metal and intermetallic layer and the pores were observed in the Ni/Ni-aluminide layers, resulting in the lower fracture resistance. With the results of acoustic emission (AE) source characterization the real time of failure and the effect of AE to crack growth could be monitored.

Chemical Homogeneity and Dispersoid Formation in Mechanically Alloyed Al-Ti Composite Metal Powders (기계적 합금화한 Al-Ti 복합금속분말의 화학적 균질성과 분산상 형성)

  • Lee, Kwang-Min;Moon, In-Hyung
    • Analytical Science and Technology
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    • v.5 no.1
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    • pp.103-110
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    • 1992
  • Chemical homogeneity and dispersoid formation in mechanically alloyed Al-Ti composite metal powders were investigated in order to fabricate the high temperature Al-Ti alloys. The homogeneity of composite particles was able to be obtained by MA milling time more than 10 hours with the milling velocity of 400 rpm. The amounts of titanium, carbon and oxygen elements in MA Al-Ti alloys by chemical analysis were 8.2, 1.135 and 0.233 wt.%, respectively. The amount of carbon analyzed corresponds to 90 pet. of carbon contained the PCA of stearic acid. TEM analysis has revealed the presence of the rounded $Al_3Ti$ dispersoids with the size of 250nm and the $Al_4C_3$ dispersoids of cylindrical shape with a size of 50nm in thickness and 150nm in length. Also, the some rounded $Al_2O_3$ dispersoids with a size of about 20nm were found in grain boundaries as well as in matrix.

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Effect of Nb, V and Cr on the High Temperature Oxidation of Ti-(42, 44)% Al Alloys (Ti-(42, 44)%Al 합금의 고온내산화성에 미치는 Nb, V 및 Cr의 영향)

  • Lee, Yeong-Chan;Kim, Mi-Hyeon;Kim, Seong-Hun;Lee, Won-Uk;Baek, Jong-Hyeon;Lee, Dong-Bok
    • Korean Journal of Materials Research
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    • v.9 no.10
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    • pp.1025-1031
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    • 1999
  • Alloys of TiAl with six different compositions. i. e., Ti-(42, 44)Al-2Nb-4V. Ti-(42, 44)Al-4Nb-2V and Ti -(42, 44)Al-4Nb-2Cr, were manufactured by arc-melting. and their oxidation behavior was studied. Both isothermal and cyclic oxidation tests were performed at 700, 800 and $900^{\circ}C$ in air for 50hr. The oxidation resistance increased in the order of Ti-(42, 44)Al-2Nb-4V, Ti-(42, 44)Al-4Nb-ZV and Ti-(42, 44)Al-4Nb-2Cr. It was found that V was a deleterious element, while Cr was a beneficial element in terms of oxidation resistance. During oxidation, a simultaneous interdiffusion was observed. All the constituent elements in the base alloys diffused outward. whereas oxygen from the atmosphere diffused inward, to form triple oxide layers composed of an outermost $\textrm{TiO}_2$ layer. upper ($\textrm{TiO}_2+\textrm{Al}_2\textrm{O}_3$) mixed layer, and lower $\textrm{TiO}_2$-rich layer.

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Comparative study on impact behavior of TiN and TiAlN coating layer on WC-Co substrate using Arc ion Plating Technique (아크이온 플레이팅법으로 WC-Co에 증착된 TiN 및 TiAlN박막의 충격특성 비교)

  • 윤순영;류정민;윤석영;김광호
    • Journal of the Korean institute of surface engineering
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    • v.35 no.6
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    • pp.408-414
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    • 2002
  • TiN and TiAlN coating layer were deposited on WC-Co steel substrates by an arc ion plating(AIP) technique. The crystallinity and morphology for the deposited coating layers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impact behaviors of the deposited TiN and TiAlN coating layer were investigated with a ball-on-plate impact tester. Beyond $10^2$ impact cycle, TiAlN coating layer showed superior impact wear resistance compared to TiN coating layer. On the other hand, both TiN and TiAlN coating layers started to be partially failed between $10^2$ and $10^3$ impact cycle. Above $10^3$ impact cycle, TiN and TiAlN coating layers showed similar impact behavior because of the substrate effect.

High Temperature Oxidation of Ti-6Al-4V, Ti-4Fe, Ti-(1,2)Si Alloys (Ti-6Al-4V, Ti-4Fe, Ti-(1,2)Si합금의 고온산화)

  • 박기범;이동복
    • Journal of the Korean institute of surface engineering
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    • v.34 no.2
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    • pp.135-141
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    • 2001
  • Arc-melted Ti-6Al-4V, Ti-4Fe and Ti-(1,2) Si alloys were oxidized at 700, 800, 900 and $1000^{\circ}C$ in air. The oxidation resistance of Ti-4Fe was comparable to that of Ti-6Al-4V, while the oxidation resistance of Ti-(1,2) Si was superior to that of Ti-6Al-4V. Ti-2Si displayed the best oxidation resistance among the four alloys, but failed after oxidation at $1000^{\circ}C$ for 17h. The oxide scale formed on Ti-6Al-4V, Ti-4Fe and Ti-(1,2)Si consisted of ($TiO_2$ and a small amount of $Al_2$$O_3$), ($TiO_2$ and a small amount of dissolved iron), and ($TiO_2$ plus a small concentration of amorphous $SiO_2$), respectively. The oxide grains of the surface scale of the four alloys were generally fine and round.

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Hybrid 공정을 이용하여 코팅 된 TiAlSiN 박막의 특성 연구

  • Kim, Seong-Hwan;Yang, Ji-Hun;Byeon, In-Seop;Jeong, Jae-In
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.130-130
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    • 2018
  • 산업 발전으로 특수합금들이 발달함에 따라 가공할 수 있는 새로운 절삭공구소재들이 개발되어지고 있다. 또한 공구소재보다 코팅개발이 상대적으로 더욱 효과적이기 때문에 코팅 기술 개발이 활발히 진행되고 있다. 일본에서는 새로운 코팅층 물질 개발보다는 기존의 코팅물질을 조합하거나 개량하여 성능을 향상시키는 추세이다. TiAlSiN 박막은 스퍼터링과 음극 아크 소스를 이용한 hybrid 공정을 이용하여 코팅 후 특성을 평가하였다. Ti-50at.%Al의 조성을 갖는 TiAl 합금 타겟은 음극 아크 소스를 이용하여 코팅하였다. 공정 가스는 Ar과 N2의 혼합 가스를 사용하였으며 공정 압력은 $1.0{\times}10^{-2}Torr$이었다. 음극 아크 소스에 인가된 전류는 70 A이었다. TiAlSiN 박막의 Si 함량을 조절하기 위해서 Si은 스퍼터링으로 코팅하였으며 스퍼터링 소스에 인가되는 전력의 세기를 0.29 kW ~ 1.05 kW까지 변화시켰다. 코팅 공정에 사용된 Si 타겟의 순도는 4N이다. TiAlSiN 박막의 Si 함량은 스퍼터링 전력에 따라 3.4 ~ 14.4at%까지 변화하는 것을 확인하였다. TiAlSiN 코팅층의 경도는 초미소 경도계를 이용하여 측정하였으며, Si 함량이 증가하면 TiAlSiN 박막의 경도도 증가하는 것을 확인할 수 있다. TiAlSiN 박막의 Si 함량이 9.2at.%일 때 3000 Hv 이상의 경도를 보였다. TiAlSiN 코팅층의 Si 함량이 14.4at%로 높아지면 경도가 낮아지는 현상을 보였다. TiAlSiN 박막의 Si 함량이 증가하면 내산화성이 향상되는 현상을 확인할 수 있었다.

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Syntheses of(Ti, Al)N Powder by the Direct Nitridation (1) (직접질화법에 의한(Ti, Al)N계 복합질화물의 합성(I))

  • Sohn, Yong-Un;Lee, Young-Ki;Hwang, Yeon;Cho, Young-Soo;Kim, Suk-Yoon
    • Journal of the Korean Society for Heat Treatment
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    • v.8 no.3
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    • pp.187-196
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    • 1995
  • TiN and AlN are ceramic materials with mechanical and chemical properties for use in structural applications at elevated temperature. The purpose of this research is to develop the technology for the synthesis of (Ti, Al)N power, which shows simultancously the excellent properties of TiN and AlN, from the mixed powder($Ti_{0.25}Al_{0.75}$, $Ti_{0.5}Al_{0.5}$ and $Ti_{0.75}Al_{0.25}$) by the direct nitriding method. The effects of variables such as temperature, mixing ratio of Al to Ti in raw material were investigated. The(Ti, Al)N powder can be easily synthesized from the mixed powder by the direct nitriding method. Among the mixed powdres, the nitriding behavior decreased with increasing the ratio of Al to Ti. This behavior is well explained by the nitriding mechanism presented in this research.

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