Abstract
The nature of surface films that form under free corrosion conditions, and their effect on the subsequent polarization behaviour of an Al-1·90Li-1·80Cu-1·00Mg-0·09Zr alloy in 0·1 mol/l NaOH solution at 35°C have been studied. The variation of open circuit potential (OCP) as a function of time is characteristic for the alloy in the electrolyte. It initially changes in the noble direction with the surface of the specimen being enveloped by a black coating, and, later, when the black coating is punctured at some localized regions, the OCP shifts and stabilizes at an active value of −1450 mV vs saturated calomel electrode (SCE). X-ray diffraction analysis of the surface film layer indicates that it consists of essentially lithium aluminum hydroxide at shorter immersion time, and lithium aluminum hydroxide and copper hydroxide after longer immersion time in the electrolyte. The scale morphology as a function of immersion time has also been studied by scanning electron microscopy. Polarization experiments conducted after 2 and 15 h of immersion revealed that the alloy exhibited active-passive type polarization behaviour in both the cases. The polarization behaviour of the specimen immersed for longer times has been explained by considering Cu ennoblement on the surface. It was also observed that the hydride LiAlH4 forms on the surface regions of the alloy under free corrosion conditions.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
