Influence of aging at 200 C on the corrosion resistance of Al-Li and AI-Li-Cu alloys

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Corrosion (Houston); (USA)

DOI:https://doi.org/10.5006/1.3577857· OSTI ID:7173243

Kumai, C; Kusinski, J; Devine, T M ^[1]; Thomas, G ^[2]

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1. California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering
2. Dept. of Materials Science and Mineral Engineering, Univ. of California, Lawrence Berkley Lab., Berkley, CA (US)

This paper presents an investigation of the influence of heat treatment on the microstructure and corrosion resistance of an aluminum lithium alloy and two aluminum-lithium-copper alloys. Aging the Al-Li alloy resulted in the precipitation of {delta} with precipitate-free zone (PFZ) formation along the grain boundaries. The intragranular precipitation of {delta} did not influence either the morphology of pitting or the magnitude of the pitting potential. Pits appeared to consist of aggregates of submicron-sized cuboidal volumes. Their faceted shape suggests the strong influence of crystallographic factors. Anodic polarization of the Al-Li-Cu alloy is the T8 condition in aqueous solutions containing chloride ions resulted in blistering of the passive film and the formation of pits that were hemispherical in shape. Aging the Al-Li-Cu resulted in the precipitation of Cu-rich phases with PFZ formation along the grain and subgrain boundaries. Energy dispersive x-ray (EDX) microchemical analyses indicated the PFZ was depleted of copper. Anodic polarization of aged samples in chloride ion media resulted in localized attack along the subgrain and grain boundaries. Such attack did not occur in solutions free of chloride ions. The electrochemical tests and microchemical analyses suggest that the boundary corrosion was caused by the pitting corrosion of copper-depleted zones.

• OSTI ID: 7173243
• Journal Information: Corrosion (Houston); (USA), Journal Name: Corrosion (Houston); (USA) Vol. 45:4; ISSN 0010-9312; ISSN CORRA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360105* -- Metals & Alloys-- Corrosion & Erosion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
AGE HARDENING
ALLOYS
ALUMINIUM ALLOYS
COPPER ALLOYS
CORROSION RESISTANCE
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
GRAIN BOUNDARIES
HARDENING
HEAT TREATMENTS
LITHIUM ALLOYS
MICROSTRUCTURE
PHASE STUDIES
SPECTRA
X-RAY SPECTRA