Discontinuities in the porous anodic film formed on AA2099-T8 aluminium alloy

The anodizing behaviour of constituent particles (Al-Fe-Mn-Cu) and dispersoids (Al-Cu-Mn-Li and beta'(Al(3)Zr)) in AA2099-T8 has been investigated. Low-copper-containing Al-Fe-Mn-Cu particles anodized more slowly than the alloy matrix, forming a highly porous anodic oxide film. Medium- and high-copper-containing Al-Fe-Mn-Cu particles were rapidly dissolved, resulting in defects in the anodic film. The anodizing of Al-Cu-Mn-Li dispersoids is slightly slower than the alloy matrix, forming a less regular anodic oxide film. beta'(Al(3)Zr) dispersoids anodized at a similar rate to the alloy matrix. Further, the potential impact of the discontinuities in the resultant anodic films on the performance of the filmed alloy is discussed. (C) 2011 Elsevier Ltd. All rights reserved.