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Vol.41, No.8, 495 ~ 503, 2003
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| Title |
| Electrochemical Characteristics of ECAPed 1050 Al alloy |
| 정민경 Jeong Min Gyeong , 최윤석 Choe Yun Seog , 김정구 Kim Jeong Gu , 김영만 Kim Yeong Man , 이재철 Lee Jae Cheol , 석현광 Seog Hyeon Gwang |
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| Abstract |
| The effect of equal channel angular pressing (ECAP) pass number on the electrochemical properties of AA 1050 (UNS A91050) in 0.1M Na₂SO₄ solution containing 100 ppm chloride were investigated by electrochemical techniques (potentiodynamic test, potentiostatic test, electrochemical impedance spectroscopy (EIS) and surface analyses (OM, SEM, EDS). The ECAPed specimens that have a various numbers of passes from N=l to N=5 were selected for electrochemical experiments in this study. The results of potentiodynamic test indicated that the breakdown potential increased with increasing the ECAP pass number. EIS measurements also showed that the corrosion resistance of the AA 1050 increased with increasing the ECAP pass number at the passivation and breakdown states. The results of surface analyses (SEM, EDS) showed that silicon-containing impurities were observed on the surface of the alloy. It was found that the size of these Si-containing impurities decreased with increasing the ECAP pass number. The Si-containing impurities induced the microgalvanic reaction(i) between the Al matrix and the Si-containing mixed oxide and (ii) between the Al matrix and the Si-containing impurities. Due to its ultrafine-grained microstructure, ECAPed AA 1050 had smaller Si-containing impurities, and reduced microgalvanic currents. Thus, in the case of ECAPed AA 1050, it has increasing corrosion resistance with increasing ECAP pass number because of its small cathodic impurities. |
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| Key Words |
| ECAP, AA 1050, Cathodic impurity, Local microgalvanic cell |
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