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Made available in DSpace on 2022-04-28T18:54:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-06-01 The 2024 and 7050 aluminium alloys used as aircraft components were subjected to laboratory corrosion tests in sodium chloride solution. Light-microscope examinations make it possible to characterise morphological aspects of the localised corrosion. Image analysis was used to determine both depth and width of pits over corroded surfaces. It has been concluded that the annealing could reduce the pit growth in both alloys, by means of grains recrystallization or recovery. The 2024 alloy also tends to present an exfoliation mechanism, mainly throughout non-recrystallized and recrystallized grain boundaries, increasing the width and sustaining the depth of pit cavities during exposition to saline atmosphere. SEM and EDS analysis reveal the morphology and elemental distribution of the corrosion products formed after immersion corrosion test. Some of these products were identified by X-ray diffraction analysis. For 2024, Al(OH)3, Mg(OH)2 and Cu2O were found. Al(OH)3 and Cu2O were also found in 7050 samples. Lab. Analise de Imagens de Materiais UNESP Campus de Guaratinguetá, Av. Dr. Ariberto Pereira Cunha 333, 12516-410 Guaratinguetá, SP Lab. Analise de Imagens de Materiais UNESP Campus de Guaratinguetá, Av. Dr. Ariberto Pereira Cunha 333, 12516-410 Guaratinguetá, SP

Made available in DSpace on 2022-04-28T19:55:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-02-01 The effects of heat treatment on morphologies and microstructures of Al 2024 and Al 7050 alloys, used as aircraft components, were studied by metallographic techniques. Light microscopy (LM) and quantitative image analysis were used to characterize the precipitate dispersion and morphology for these alloys. The application of the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) combined techniques for studying these multiphase systems makes it possible to distinguish and quantity the different phases in the surface structure. X-ray diffraction also permitted a qualitative comparison of the structures before and after heat treatments. Depto. de Materiais e Tecnologia Faculdade de Engenharia - UNESP, Av. Dr. Arib. Pereira da Cunha 333, 12500-000, Guaratinguetá, SP Depto. de Materiais e Tecnologia Faculdade de Engenharia - UNESP, Av. Dr. Arib. Pereira da Cunha 333, 12500-000, Guaratinguetá, SP