• Title/Summary/Keyword: Alloys

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Mechanical Properties of Al-Ti Base Alloys Processed Via Rapid Solidification and Mechanical Alloying (급냉응고 및 기계적 합금화된 Al-Ti계 합금의 기계적 성질)

  • 최철진
    • Journal of Powder Materials
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    • v.2 no.1
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    • pp.36-43
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    • 1995
  • Rapidly solidified and mechanically alloyed Al-Ti base alloys were prepared by gas atomization and attritor milling separately. The gas atomized and the mechanically alloyed powders were consolidated after preheating at $450^{\circ}C$, and then heat treated isochronally for 1 hour to observe the microstructures and to investigate the mechanical properties. Stable phases of precipitates in the Al-Ti-Si and the Al-Ti-Zr alloys were identified as DO22-$(Al,Si)_3Ti$ and $Do_{23}-Al_3(Ti, Zr)$ each. Among the alloys, the mechanically alloyed Al-l0Ti-2Si alloy showed superior thermal stability and mechanical properties at elevated temperature. The additions of third elements, such as Si and Zr, to Al-Ti alloys seemed to improve the mechnical properties remarkably by stabilizing the microstructure and the precipitate phases in the consolidated alloys.

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COMPARATIVE STUDY ON THE CASTABILITY OF VARIOUS ALLOYS FOR PORCELAIN-FUSED-TO-METAL CROWN (도재소부전장주조관(陶材燒付前裝鑄造冠)에 사용(使用)되는 각종(各種) 합금(合金)의 주조성(鑄造性)에 관(關)한 비교연구(比較硏究))

  • Lee, Tae-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.18 no.1
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    • pp.87-97
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    • 1980
  • To compare the castability of various alloys popularly used in Korea for porcelain-fused-to-metal restorations, author selected Degudent G as precious alloy, J.P. 92 as semiprecious alloy and Vera Bond, Rexillium III, Unit Bond, Fine Bond as non precious alloys. With nylon lines and gauge waxes, author made the wax patterns for the castability comparison test. In the same conditions, wax patterns were invested, burned out and cast. Author obtained the following results from this study. 1. The castability of Degudent G as precious alloy for porcelain-fused-to-metal crown and bridge was the best of all. 2. The castability of nonprecious alloys was less than Degudent G as precious alloy, but their differences were not large. 3. The castability of Rexillium III is the best of all nonprecious alloys and that of Vera Bond, Unit Bond had nearly the same results. 4. Semiprecious alloy (J.P. 92) was less castable than nonprecious alloys.

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Effect of TiC Content on Oxidation Behavior of Sintered WC-TiC-TaC Alloys

  • Tanaka, Hiroki;Mouri, Shigeki;Nakahara, Kenji;Sano, Hideaki;Zheng, Guo Bin;Uchiyama, Yasuo
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.352-353
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    • 2006
  • The effect of TiC content on oxidation behavior of the sintered WC-TiC-TaC alloys with 2 mass% TaC and different TiC amounts of 3-45 mass% was investigated through oxidation tests in air at 973K. As a result of the tests, it was revealed that with increasing TiC content in the alloys, mass changes caused by oxidation and thickness of the scale decreased. Thus, it is considered that the main component of the scales changed gradually from $WO_3$ to $TiO_2$ with increasing TiC content in the alloys, and oxygen diffusion through the scale to the alloys was inhibited gradually.

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A Study on Stress Corrosion of Al-8ti-1B Alloys by Mechanical Alloying (기계적 합금화한 Al-8Ti-1B 합금의 응력부식에 관한 연구)

  • 김기주;강성군;백영남
    • Journal of the Korean institute of surface engineering
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    • v.27 no.4
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    • pp.215-222
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    • 1994
  • The role dispersoids has been studied in a number of researches as a key point for the high strength application of dispersion strengthened aluminum alloy. The mechanical alloying(MA) process with high mechanical properties of dispersion strengthened MA Al-8Ti-1B alloys were invested in order to evaluate their stress corrosion cracking(SCC) application. SCC properties of the mechanically alloyed Al-8Ti-1B were studied using slow strain rate test(SSRT). In this study Al-8Ti-1B alloy were more susceptible to SCC in solutions of pH=2.01 and 13.2 than pH=6.81 solution. In this study Al-8Ti-1B alloys by MA had more SCC resistance than Al-8Ti alloys or Al 7075-T73 alloys. So Al-8Ti-1B alloys by MA had more resistance in SSRT SCC susceptinility test than any other above alloying metals.

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Effect of Fe on the High Temperature Oxidation of TiAl Alloys (TiAl 합금의 고온 산화에 미치는 Fe의 영향)

  • 김미현;이동복
    • Journal of the Korean institute of surface engineering
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    • v.33 no.4
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    • pp.281-288
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    • 2000
  • To understand the effect of Fe on the oxidation behavior of TiAl alloys, TiAl-(2, 4, 6at% )Fe were oxidized at 800 and 90$0^{\circ}C$ in air. The oxidation resistance of TiAl-Fe alloys increased with increasing an iron content. The scales formed consisted of an outer $TiO_2$ layer, an intermediate $A1_2$$O_3$ layer, and an inner mixed ($TiO_2$+$A1_2$$O_3$) layer, being similar to other common TiAl alloys. But, the scales formed on TiAl-Fe alloys were generally thin compared to those formed on pure TiAl, and contained dissolved iron. Below the oxide scale, an oxygen affected zone was formed. This beneficial effects of Fe on increasing the oxidation resistance and scale adherence of TiAl alloys were attributed to the refinement of oxide grains, increased scale adherence and the enhanced alumina-forming tendency.

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High Efficient Welding Technology of the Car Bodies (자동차 경량화를 위한 알루미늄 합금의 강변형 가공 및 고능률 용접기술에 관한 동향)

  • Kim, Hwan Tae;Kil, Sang Cheol
    • Journal of Welding and Joining
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    • v.34 no.4
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    • pp.62-66
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    • 2016
  • The trend of the fabrication technology of high strength, high toughness aluminum alloys by the severe plastic deformation(SPD) process and the welding technology of lightweight alloys in the automobile has been studied. The lightweight aluminum alloys can reduce vehicle weight, while stringently demanding the high quality and efficient welding techniques, to produce the best weldments. Among the production technologies, welding plays an important role in the fabrication of lightweight vehicle structure. This paper covers the scientometric analysis of the severe plastic deformations of lightweight alloys and the welding technology in the automobile which are based on the published research works in the 'HPT, ECAP and rolling', and 'welding technology of the automobile' obtained from Web of Science, and deals with the details of the background data of the HPT, ECAP, and rolling of lightweight alloys, and welding technology of the automobile technology.

Structural Analysis of Simulated Fission-Produced Noble Metal Alloys and Their Superconductivities

  • Park, Yong Jun;Lee, Gwang Yong;Lee, Jong Gyu;Heo, Yong Deuk;Kim, Won Ho
    • Bulletin of the Korean Chemical Society
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    • v.21 no.12
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    • pp.1187-1192
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    • 2000
  • Ternary (Mo-Ru-Pd) and binary (Mo-Ru, Mo-Pd) alloys have been prepared using an Ar arc melting furnace. Mo and the noble metals, Ru and Pd, are the constituents of metallic insoluble residues, which were found in the early days of post-irradiation studies on uranium oxide fuels. In the present study, the structure of the alloys was evaluated using a powder X-ray diffractometer. Unit cell parameters were determined by least squares refinements of powder X-ray diffraction data. Scanning electron microscopic analyses of the surface of the alloys indicated that surface morphology was dependent on the crystallographic structure as well as its composition. Measurements of the magnetic susceptibility of the alloys showed evidence of superconducting transition from 3 to 9.2 K. Among the ternary and binary alloys, the ${\sigma}-phase$ showed the highest superconducting transition temperature,~9.2 K.

An extensive investigation on gamma ray shielding features of Pd/Ag-based alloys

  • Agar, O.;Sayyed, M.I.;Akman, F.;Tekin, H.O.;Kacal, M.R.
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.853-859
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    • 2019
  • A comprehensive study of photon interaction features has been made for some alloys containing Pd and Ag content to evaluate its possible use as alternative gamma radiations shielding material. The mass attenuation coefficient (${\mu}/{\rho}$) of the present alloys was measured at various photon energies between 81 keV-1333 keV utilizing HPGe detector. The measured ${\mu}/{\rho}$ values were compared to those of theoretical and computational (MCNPX code) results. The results exhibited that the ${\mu}/{\rho}$ values of the studied alloys are in the same line with results of WinXCOM software and MCNPX code results at all energies. Moreover, Pd75/Ag25 alloy sample has the maximum radiation protection efficiency (about 53% at 81 keV) and lowest half value layer, which shows that Pd75/Ag25 has superior gamma radiation shielding performance among the other compared alloys.

Effects of Nb Addition on Corrosion Resistance and Cytotoxicity Behavior of Ti Alloys (Nb이 첨가된 Ti합금의 내식성 및 생체안정성)

  • Lee, Doh-Jae;Lee, Kwang-Min;Lee, Kyung-Ku;Ryu, Chang-Nam;Oh, Tae-Wook;Kim, Soo-Hag;Yoon, Tack-Lim
    • Korean Journal of Materials Research
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    • v.13 no.11
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    • pp.761-768
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    • 2003
  • The corrosion resistance and cytotoxicity behavior of Ti alloys were studied as a function of Nb contents(3wt.%Nb, 20wt.%Nb, 40wt.%Nb). Ti-Nb alloys were melted by vacuum arc furnace and then rolled to 50% reduction ratio after homogenized at 105$0^{\circ}C$ for 24hrs. The corrosion resistance of Ti-Nb alloys were investigated by potentiodynamic polarization test in the 0.9% NaCl and 5% HCI solution. Biocompatibility of Ti-Nb alloys was evaluated by cytotoxicity test. The results can be summarized as follows 1) The microstructure change from equiaxial to acicular and the increased $\beta$ phase in Ti-Nb alloys were obtained as the Nb content increased. 2) For the corrosion test in the solution of 0.9% NaCl and 5% HCI, the corrosion behavior of Ti-Nb alloys was similar to ASTM grade 2 CP Ti. 3) For the cytotoxicity test, Ti-Nb alloys showed excellent biocompatibility compared to ASTM grade 2 CP Ti, 316L STS and Co-Cr alloys.