Oxide Film Destruction on Al-Mg Alloys in HCl Solutions

Abstract

Open circuit potential technique is used to follow the oxide film destruction of three of Al-Mg alloys in HCl solutions of varying concentrations.  Dissolution of the passive film on pare metal surface takes place in two distinct steps indicating that the film is composed mainly of a barrier layer of Al₂O₃ adjacent to the metal surface and an outer porous modification on the top of the first one. The rates of oxide film destruction and/or dissolution (δ₁¯ and δ₂¯) follow a direct logarithmic law. The extent of oxide film destruction and metal dissolution were found to increase with increasing the acid concentration and the percent of Mg content in the alloy sample.