A review of recent research on the corrosion behaviours and mechanism of Al-Cu-Li alloys

Al-Cu-Li alloys are one of the best materials for structural components of aerospace vehicles due to their comprehensive exceptional qualities. Recently, the growing application requirement for the high performance and corrosion resistance of Al-Cu-Li alloy has been a popular research focus in the aerospace field. However, the relatively low corrosion resistance was displayed in the aged Al-Cu-Li alloy due to the active element Li addition; the ways of addition of micro-alloying elements and heat treatment controlling employed to weaken the corrosion propagation behaviours were investigated in the past decades. Recent research given critical factors and mechanisms of corrosion behaviours (e.g., IGC, EXCO and SCC) of Al-Cu-Li alloys were reviewed in this paper. These factors include additional elements, ageing heat treatment, heat treatment before solution heat treatment, thermo-mechanical processing, precipitations, grain structure characteristics, and corrosion electrochemistry behaviours. Lastly, a new concept of the first generation of corrosion-resistant high-performance Al-Cu-Li alloys was proposed from the perspective of composition design. The composition design of the emerging fourth-generation corrosion-resistant Al-Cu-Li alloy should be of a suitable Cu/Li ratio with the addition of Zn and Ag. This new concept alloy was proposed to apply the three-dimensional characterization and the visual simulation to guarantee the optimized high-strength and high corrosion resistance.