Corrosion maps for aluminium alloys

Aluminium alloys are widely used in various applications due to their high strength to weight ratio. They are generally passive and corrosion resistant in aqueous solutions but prone to pitting corrosion in the presence of reactive species, particularly halide ions. In this work, we closely survey the corrosion behaviour of several commercially available aluminium alloys in 0.1M sodium chloride solution. The corrosion rates for these alloys were determined by a battery of tests including potentiodynamic polarisation, electrochemical impedance spectroscopy and weight loss. This allowed for the ability to carefully rank the performance of different alloys with higher fidelity than what is available in the literature. The results obtained from these tests were then compared to the alloys mechanical strength to establish a relationship that we define as a 'corrosion map' of the i corr vs σ yield (or i corr vs HVN) property space. This map can be utilised to rationalise the development of new aluminium alloys with superior corrosion resistance while maintaining mechanical strength.