Abstract
The anodic dissolution characteristics of Al2Cu intermetallic compounds which is stoichiometric or Al-rich specimens are investigated by the measurements of an electrochemical method such as anodic polarization curves and potentiostatic dissolution tests, immersed corrosion tests and scanning electron microscopic observations of corroded surfaces for the specimens in a dilute HClO4 solution.
The main results obtained are summarized as follows:
(1) The anodic polarization curves of Al2Cu intermetallic compound specimens in a dilute HClO4 solution show a typical active-passive transition, and the limiting anodic current density of the specimens increases with an increase in the concentration of HClO4 and the solution temperature irrespective stoichiometries of the specimens. However, the anodic dissolution rate of the Al-rich specimen is larger than that of stoichiometric ones under the same conditions.
(2) The activation energies of anodic dissolution of Al2Cu are 27.6 kJ/mol for the Al-rich specimen and 48.5 kJ/mol for the stoichiometric ones.
(3) The proposed anodic dissolution mechanism for Al2Cu intermetallic compound specimens in the dilute HClO4 solution under the potentiostatic condition is shown in the following equations:
The selective anodic dissolution of Al species from the stoichiometric Al2Cu intermetallic compound:
(This article is not displayable. Please see full text pdf.)
\
oindentThe selective anodic dissolution of Al species from the eutectic phase in the Al-rich Al2Cu intermetallic compound specimen:
(This article is not displayable. Please see full text pdf.)
