Microstructural, Electrochemical and Localized Corrosion Characterization of the AA2198-T851 Alloy

Abstract

In the present work, the microstructure, electrochemical behavior and localized corrosion of the AA2198-T851 Al-Cu-Li alloy were studied. The microstructure was correlated with corrosion results obtained by immersion, gel visualization and scanning electrochemical microscopy (SECM) tests. Immersion and gel visualization tests showed high kinetics of corrosion attack during the first hours of immersion. SECM analyzes by means of surface generation/tip collection (SG/TC) mode detected hydrogen evolution generated during spontaneous corrosion from severe localized corrosion (SLC) sites on the metal surface. SECM results revealed sites of intense hydrogen evolution after 2 h of immersion and increased amounts of corrosion products after 4 h of immersion. Hydrogen evolution sites detected by SECM were associated with severe localized corrosion (SLC).

TSA anodising voltage effects on the near-surface coarse intermetallic particles in the AA2024-T3 and AA2198-T8 alloys

“…In the last years, many works were carried out in order to understand the corrosion mechanism and the corrosion resistance of the AA2024 alloy [18 28,12] and also of the Al-Cu-Li alloys [4,11,29 37]. Recently, some researchers reported the effect of microstructure on the corrosion initiation in Al-Cu and Al-Cu-Li alloys [38 54]. All these works demonstrated the higher susceptibility of these alloys to localised corrosion and the need for corrosion protection.…”

“…The AA2198 alloy has been the object of numerous corrosion studies [4,11,30,42,43,88 93]. However, the behaviour of the coarse intermetallic particles during anodising has not yet been reported.…”

The Potentialities of Raman and XPS Techniques to Evaluate the Corrosion Products Formed on the 2198-T851 Aluminium Alloy Exposed to Sodium Chloride Solution

“…Another corrosion mechanism may be related to the existence of T 1 nanometric particles as displayed in Figure 5a. As mentioned by Moreto et al 20 and confirmed by Araújo et al 21 , when 2198-T851 aluminium alloy is exposed to a corrosive environment, T 1 precipitates are anodic with respect to the aluminium matrix, promoting their dissolution. As the corrosion process progresses, T 1 becomes cathodic due to the selective dissolution of aluminium and lithium elements, increasing the Cu amount on the 2198-T851 aluminium alloy matrix as represented by Figure 5b.…”

Influence of chloride ions concentration on the development of severe localised corrosion and its effects on the electrochemical response of the 2198-T8 alloy

“…Luo et al [42] also discussed the corrosion reactions and their influences on alkalinisation/acidification during the exposure of an Al–Cu–Li alloy to 3.5% NaCl solution. In our previous work [43], agar gel visualisation technique was used to monitor the pH variations on the surface of a 2198-T851 alloy. Owing to the low mobility of ions in the gel, the result from the agar gel test does not represent the real conditions of aqueous environments.…”