期刊
MATERIALS & DESIGN
卷 83, 期 -, 页码 193-202出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.matdes.2015.06.018
关键词
Al-7Si alloys; High-pressure torsion; Grain refinement; Corrosion resistance; Microhardness; Electrochemical impedance spectroscopy
资金
- China Scholarship Council
- University of Southampton
High-pressure torsion (HPT) was used to produce hypoeutectic Al-7Si alloy samples having a range of microstructures to investigate the effect of the grain refinement on its corrosion behavior in 3.5 wt.% NaCl solution for the first time. Optical microscopy measurements reveal that with the HPT processing increased from 1/4 to 10 revolutions under an applied pressure of 6.0 GPa, brittle coarse silicon particles and intermetallic phases were effectively broken into ultrafine-grained particles and redistributed homogeneously into the Al-rich matrix. Open-circuit potential and polarization curves results exhibit that corrosion resistance of the Al-7Si alloy in NaCl solution was significantly enhanced upon high torsion strains, with corrosion rate reduced from 7.41 mu m y(-1) for the as-received sample to 1.68 mu m y(-1) for the 10-turn processed sample. Electrochemical impedance spectroscopy analysis combined with characterization of the corroded samples using scanning electron microscopy and energy dispersive X-ray spectroscopy indicates that the enhancement in corrosion performance of the Al-7Si alloy is due to the breakage of coarse silicon particles and intermetallic phases, the microstructure homogeneity and the increased HPT-induced active sites. It is demonstrated that microstructure refinement through HPT processing can significantly improve both microhardness and corrosion properties of the Al-7Si alloy. (C) 2015 Elsevier Ltd. All rights reserved.
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