The Open Corrosion Journal

2010, 3 : 73-79
Published online 2010 August 17. DOI: 10.2174/1876503301003010073
Publisher ID: TOCORRJ-3-73

The Role of MgSi in the Corrosion Behavior of Al-Si-Mg Alloys for Pressureless Infiltration

R. Escalera-Lozan , M.I. Pech-Canul , M. A. Pech-Canul , M. Montoya-Dávila and A. Uribe-Salas
Cinvestav Mérida. Km. 6 Antigua Carretera a Progreso Apdo. Postal 73, Cordemex. Mérida, Yuc., 97310, México

ABSTRACT

The role of Mg2Si in the electrochemical behavior of Al-Si-Mg aluminum alloys has been studied using four experimental aluminum alloys with variations in the Si/Mg molar ratio (A1-0.12, A2-0.49, A3-0.89, A4-1.05), in neutral aerated 0.1M NaCl solutions. Accordingly, the corrosion potential in open circuit (Eoc) and polarization resistance (Rp) were measured. Results show that the augment in Si/Mg molar ratio increases the presence of Mg2Si intermetallic phase. During immersion tests in neutral aerated chloride solutions the anodic activity of the Mg2Si intermetallic decreased rapidly, as indicated by a fast ennoblement of open circuit potential. After the immersion period (7 days), higher Rp values for alloys A3 and A4 (21 and 26 KΩcm2, respectively) as compared to those for alloys A1 and A2 (5 and 10 KΩcm2, respectively), suggest a greater corrosion resistance in Cl- containing environments for alloys A3 and A4.

Keywords:

Al-Si-Mg alloys, corrosion potential, polarization resistance, NaCl solutions, MgSi.