TY - JOUR
T1 - Synergetic effect of Mg2Si and Si particles on intergranular corrosion of Al-Mg-Si alloys through multi-electrode coupling system
AU - Li, Chaoxing
AU - Li, Jinfeng
AU - Birbilis, Nick
AU - Jia, Zhiqiang
AU - Zheng, Ziqiao
PY - 2010/10/11
Y1 - 2010/10/11
N2 - The potentiodynamic scanning curves and the electrochemical coupling behaviors of constituent phases at the grain boundary of Al-Mg-Si alloy were investigated. The corrosion mechanism of Al-Mg-Si alloys different ratio of Mg to Si was analyzed. The results show that the Si particle is cathodic to the Al-base and causes the anodic dissolution of Al-base at its adjacent periphery. At the beginning, the precipitate of Mg2Si is anodic to the Al-base and corrosion occurs on its surface. However, during its corrosion process, its potential moves to a positive direction with immersion time increasing, due to the preferential dissolution of Mg and the enrichment of Si, which makes Mg2Si become cathodic to Al-base and leads to the anodic dissolution of the Al-base at its adjacent periphery at a later stage. At the grain boundary of Al-Mg-Si alloys with a ratio of Mg to Si higher than 1.73, the Mg-and-Si contained precipitates are distributed discontinuously, resulting in that they are not sensitive to intergranular corrosion. There exist Mg-and-Si-contained precipitates and Si particles at the grain boundary of Al-Mg-Si alloys with a ratio of Mg to Si less than 1.73, corrosion occurs firstly on the surface of Mg2Si. Meanwhile, the Si particle leads to the great anodic dissolution of the precipitate-free-zone(PFZ) at its adjacent periphery. The Si particle also accelerates the preferential dissolution of Mg in Mg2Si precipitate, expediting the polarity transformation between Mg2Si and the PFZ. As a result, the corrosion development along the PFZ at the adjacent of Mg2Si particle is enhanced.
AB - The potentiodynamic scanning curves and the electrochemical coupling behaviors of constituent phases at the grain boundary of Al-Mg-Si alloy were investigated. The corrosion mechanism of Al-Mg-Si alloys different ratio of Mg to Si was analyzed. The results show that the Si particle is cathodic to the Al-base and causes the anodic dissolution of Al-base at its adjacent periphery. At the beginning, the precipitate of Mg2Si is anodic to the Al-base and corrosion occurs on its surface. However, during its corrosion process, its potential moves to a positive direction with immersion time increasing, due to the preferential dissolution of Mg and the enrichment of Si, which makes Mg2Si become cathodic to Al-base and leads to the anodic dissolution of the Al-base at its adjacent periphery at a later stage. At the grain boundary of Al-Mg-Si alloys with a ratio of Mg to Si higher than 1.73, the Mg-and-Si contained precipitates are distributed discontinuously, resulting in that they are not sensitive to intergranular corrosion. There exist Mg-and-Si-contained precipitates and Si particles at the grain boundary of Al-Mg-Si alloys with a ratio of Mg to Si less than 1.73, corrosion occurs firstly on the surface of Mg2Si. Meanwhile, the Si particle leads to the great anodic dissolution of the precipitate-free-zone(PFZ) at its adjacent periphery. The Si particle also accelerates the preferential dissolution of Mg in Mg2Si precipitate, expediting the polarity transformation between Mg2Si and the PFZ. As a result, the corrosion development along the PFZ at the adjacent of Mg2Si particle is enhanced.
KW - Al-mg-si alloys
KW - Corrosion mechanism
KW - Intergranular corrosion
UR - http://www.scopus.com/inward/record.url?scp=77957588598&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:77957588598
SN - 1005-4537
VL - 30
SP - 107
EP - 113
JO - Journal of the Chinese Society of Corrosion and Protection
JF - Journal of the Chinese Society of Corrosion and Protection
IS - 2
ER -