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Artigo IPEN-doc 25934 Thermomechanical treatment and corrosion resistance correlation in the AA2198 Al–Cu–Li alloy2019 - ARAUJO, JOAO V. de S.; BUGARIN, ALINE de F.S.; DONATUS, UYIME; MACHADO, CARULINE de S.C.; QUEIROZ, FERNANDA M.; TERADA, MAYSA; ASTARITA, ANTONELLO; COSTA, ISOLDAThe influence of T3, T8 and T851 thermomechanical treatments on the microstructure and corrosion resistance of the AA2198 was investigated. Differential scanning calorimetry and scanning electron microscopy were used for microstructural characterisation, whereas electrochemical methods were employed to analyse the corrosion behaviour of the alloy. The morphology and composition of constituent particles were similar for the T3 and T8 thermomechanical treatments but varied in the T851. There was an inverse relation between T1 phase density and corrosion resistance. The T3 treatment with the highest corrosion resistance was the one with the lowest density of T1 phase. The mechanisms of corrosion varied with the thermomechanical treatments.Resumo IPEN-doc 23664 Efeito da selagem hidrotérmica com adição de íons Ce (III) na proteção à corrosão da liga de alumínio AA7475-T761 anodizada em banho ácido tartárico-sulfúrico2016 - ALMEIDA, THALLIS L.; QUEIROZ, FERNANDA M.; TERADA, MAYSA; COSTA, ISOLDA; CAPELOSSI, VERA R.The aluminum alloys of series 7XXX have excellent mechanical properties combined with low density and are often used in the aeronautic industry. However, their susceptibility to localized corrosion requires the use of protective coatings to ensure their long-term life. In the aircraft industry, the anodization process is an effective corrosion control method. Besides, the anodized layer sealing treatment of parts that are not used with coatings, provide further protection. However, both processes, anodization and sealing, generally employ baths containing Cr (VI) ions. These are highly toxic to the environment and carcinogenic. In this work, the AA7475-T761 alloy was anodized in a solution of tartaric-sulfuric acid (TSA) and then the anodic layer was hydrothermally sealed in aqueous solutions, either with or without the addition of Ce (III) ions. The effect of sealing time on the corrosion protection of the anodic layer was investigated for periods of sealing corresponding to 2.5 min, 5 min, 7.5 min and 10 min. The corrosion resistance of the anodized alloy samples was evaluated by electrochemical impedance spectroscopy (EIS) as a function of exposure time to a sodium chloride electrolyte. Higher impedances were associated with anodic layers hydrothermally sealed for 7.5 min and 10 min in Ce (III) ions containing solution. Surface observation was carried out by scanning electron microscopy (SEM) and the results indicated that hydrothermal treatments in solution with Ce (III) ions leads to anodic layers with decreased porosity.