Effect of chloride ion concentration during corrosion of medium strength alloys 8090, 2091, and 2014

The effects of chloride ion concentration on the corrosion behaviour of two Al–Li–Cu–Mg–Zr (8090 and 2091) alloys were studied and compared with that of a standard aircraft alloy, namely Duralumin (Al–Cu (2014)). Constant exposure and potentiodynamic polarisation studies were conducted in NaCl solutions (pH 10·0) of various concentrations. The corrosion rates of the lithium containing alloys decreased with increasing chloride ion concentration. The pitting potentials for the Al–Li alloys were slightly lower than that of 2014. The effect of chloride ion concentration (in the range 1–10%) on passive current density is lower by 4–5% for Al–Li alloys than for 2014. Topographic studies of the exposed specimens indicated extensive localised attack on all the alloys.