Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (01): 163-168.

• QUANTUM CHEMISTRY AND COMPUTATION CHEMISTRY •

### Electrochemical Dissolution Trends of Pb-Containing Al Alloy Surfaces

LIU Jian-Cai, ZHANG Xin-Ming, CHEN Ming-An, TANG Jian-Guo, LIU Sheng-Dan

1. School of Materials Science and Engineering, Central South University, Changsha 410083, P. R. China
• Received:2009-08-25 Revised:2009-10-29 Published:2009-12-29
• Contact: ZHANG Xin-Ming E-mail:xmzhang_cn@yahoo.cn

Abstract:

A simplified slab model was used to evaluate the effect of Pb content at the Al(100) surface on the chemical potentials and electrochemical dissolution potentials for pure Al and Al-Pb alloys using first-principles density functional theory calculations. Results indicated that the chemical potentials of the surface Al atoms, increased 0.13, 0.17, 0.57, and 0.64 eV, and their dissolution electrode potentials shifted -0.04, -0.06, -0.19, and -0.21 V with regards to pure Al when the content of Pb on the Al(100) surface was 1/9, 1/4, 1/2, and 3/4 monolayer coverages, respectively. The negative potential shift of the Pb-containing Al alloy indicates easier dissolution compared to the pure Al surfaces. The presence of Pb results in an inner relaxation of the Al surface atoms, and the surface structure as well as chemical environment changes. The chemical potential and the dissolution electrode potential are shown to be dependent on the chemical environment of the surface atoms. A Mulliken charge population analysis also indicate that at higher Pb content, the electron exchange between Pb and Al atoms increase, which results in a negatively charged aluminum surface and a reduced surface potential; the surface work function decreases, and this promotes the electrochemical corrosion of the aluminumsurface.

MSC2000:

• O641