Electrochemical behavior and surface chemistry of non‐equilibrium aluminum–tantalum alloys: Solute‐rich interphase mechanisms

The electrochemical behavior and surface chemistry of sputter‐deposited non‐equilibrium stainless Al–Ta alloys have been investigated. These alloys exhibit enhanced passivity over a pH range of 2–12 even though the passive film chemistry varies considerably over this range. This enhanced passivity can be explained by the solute‐rich interphase mechanism (SRIM), which states that formation and passivation of occluded cells are controlled by localized concentrations of solute. The higher concentrations of solute at the metaloxide interface and around occluded cells stabilize the passive‐film from continued Cl⁻ attack and dissolution.