document: AA 2024-T3 aluminium alloy is widely used for aerospace applications due to its high strength to weight ratio and high damage tolerance that result from copper and magnesium as the principal alloying elements and appropriate thermomechanical processing. The microstructure of the alloy is relatively complex and a number of compositionally-distinct phases have been identified [1]. Although possessing favourable mechanical properties, the alloy is relatively susceptible to corrosion and generally requires surface treatment in practical applications. The corrosion behaviour of the alloy is particularly affected by the presence of the intermetallic particles due to their differing potentials with respect to the alloy matrix [2–9]. Copper-containing second phase particles at the alloy surface are particularly detrimental to the corrosion resistance as they provide preferential cathodic sites [2,10]. One of the principle types of second phase particle that is important to the corrosion behaviour of the alloy is the S phase (Al2CuMg) particle [1,11]. Dealloying of S phase particles, which may account for ∼60% of the constituent particles in AA2024 alloys [11], is commonly observed when the alloy is exposed to an aggressive environment. The particles are considered as important initiation sites for severe localized corrosion in the alloy [11–22]. The dealloying of the S phase particles and the resulting enrichment of copper result in a decrease of the Volta potential with respect to the matrix and hence the dealloyed particles become active cathodic sites [23–25].
extractive_keyphrases: aa2024 alloys aerospace applications al2cumg alloy alloying elements cathodic sites constituent particles copper corrosion dealloyed particles dealloying decrease of the volta potential enrichment intermetallic particles magnesium particles second phase particle s phase surface treatment thermomechanical processing
abstractive_keyphrases: aa 2024-t3 aluminium alloy alloy matrix compositionally-distinct phases copper-containing second phase particles corrosion behaviour corrosion resistance s phase particles