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Vol.36, No.9, 1415 ~ 1421, 1998
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| Title |
| Microstructural Evolution during the Superplastic Deformation of Zn-0.3wt.% Al alloy |
| 이원절 , 박찬경 , 하태권 , 손중락 , 장영원 W . B . Lee , C . G . Park , T . K . Ha , J . R . Son , Y . W . Chang |
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| Abstract |
| The superplastic deformation of Zn-0.3wt.%Al alloys were investigated at room temperature under various strain rate. These alloys were highly elongated up to 1400% at the initial strain rate of 2×10^(-4)/s, revealing the rate sensitivity parameter of about 0.4. In order to investigate the microstructural change during superplastic deformation, the transmission electron microscopy(TEM) studies were performed on the specimen elongated up to the 100% tensile strain at various strain rate. The microstructure was composed of zinc rich matrix phase, with 1㎛ in grain size, and Al rich second phases precipitated generally at grain boundaries and/or triple point. In region III(5×10^(-2)/s), the high density of dislocations were observed within the grains and deformation twins were also formed within the grains. In region II(2^＊10^(-4)/s), however, the dislocations were highly localized along the grain boundaries and deformation twins were not observed. Observation of severe deformation along the grain boundaries and grain boundary migration(GBM) suggest that grain boundary sliding(GBS) is a dominant mechanism of superplastic deformation in this alloy. |
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