Qualitative and quantitative characterization of aluminium alloys after corrosion testing

The 2024 and 7050 aluminium alloys used as aircraft components were subject ed to laboratory corrosion tests in sodium chloride solution, Light-microsc ope examinations make it possible to characterise morphological aspects of the localised corrosion. Image analysis was used to determine both depth an d width of pits over corroded surfaces. It has been concluded that the anne aling could reduce the pit growth in both alloys, by means of grains recrys tallization or recovery. The 2024 alloy also tends to present an exfoliatio n mechanism, mainly throughout non-recrystallized and recrystallized grain boundaries, increasing the width and sustaining the depth of pit cavities d uring exposition to saline atmosphere. SEM and EDS analysis reveal the morp hology and elemental distribution of the corrosion products formed after im mersion corrosion test. Some of these products were identified by X-ray dif fraction analysis. For 2024, Al(OH)(3), MS(OH)(2) and Cu2O were found. AI(O H)(3) and Cu2O were also found in 7050 samples.