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니켈 첨가에 의한 탄성 100 GPa급 알루미늄 주조재 개발
이태규,이후담,이종국 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.12
In this research, we studied the effects of Ni, Ti, and B on the elastic modulus of hypereutectic Al-Si alloys and successfully synthesized 100 GPa Al casting alloys by designing various alloys phases. Generally, Al–Si based alloys are known in the automotive industry to be good casting alloys with high wear resistance, low thermal-expansion coefficient, good corrosion resistance at a wide range of temperatures, especially for cylinder blocks, cylinder heads, pistons and valve lifters, but the low elastic modulus of the alloys remaines a weakness. Previously, the elastic modulus of eutectic Al-Si casting alloys was enhanced by 10 GPa by strengthening phases with added Ti and B. However, elastic modulus was not enhanced by increasing Si content in the hypereutectic Al-Si alloys, since Si only reacts with the Ti containing strengthening phase. We overcame this problem by adding Ni to Ti and B containing hypereutectic Al-Si alloys. The effects of the strengthening phases produced by the addition of Ni, such as AlNi, AlNiCu, on the elastic modulus were studied, and we observed a two-fold enhancement in the wear resistance of the Ni, Ti, and B containing hypereutectic Al-Si alloys. The rate of strengthening by phases in the alloys was qualitatively analyzed by EPMA (Electron probe micro-analyzer), SEM (Scanning Electron microscopy), etc, and their mechanical properties were quantitatively evaluated by elastic modulus measurement and pin-on tester.
반사도와 색 차 분석을 이용한 Cu-Zn 합금의 색 변화 고찰
정연범,홍성환,박혜진,김영석,김정태,이후담,황윤중,이영훈,김기범 대한금속·재료학회 2018 대한금속·재료학회지 Vol.56 No.3
The change in reflectivity of Cu-Zn alloys was investigated with the modulation of Zn content. The reflectivity of the prepared alloys were compared with pure copper and divided into wavelength regions corresponding to blue, green, yellow, and red colors. As the amounts of Zn increased, the difference in reflectivity of the yellow region increased, and that of the red region decreased. To determine the color difference, the measured reflectivity of the alloys was transformed into a tristimulus value using the Reflectance-Tristimulus value converting equation. Then the tristmulus value was converted into the CIE L*a*b* color space. The color difference was calculated using the color difference formula of the converted L* a*b* values. When 5 at%Zn was added, the color difference value was 3.224, and it increased with increasing Zn content. As the difference in the reflectivity of the green and yellow regions increased, the b* value of the alloys increased and the a* value of the alloys decreased. In this study, the addition of Zn content to Cu alloy induced changes in the reflectivity of the green and yellow wavelength regions, which influences color differences of α-Cu solid solution alloys.