Evolution of the chemistry of passive films of sputter-deposited, supersaturated Al alloys. Annual report, 1 July 1987-30 November 1988

Technical Report · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5931309

Davis, G D; Moshier, W C; Fritz, T L; Cote, G O; Long, G G

Aluminum and conventional aluminum alloys are readily susceptible to localized attack in chloride-containing environments. Recently, under funding from the Office of Naval Research, we have investigated the passivity and corrosion behavior of several super-saturated aluminum alloys formed by co-sputter deposition. This report shows that several of these alloys exhibit superior resistance to localized attack in electro-chemical polarization measurements and salt-fog tests. X-ray photoelectron spectroscopy was used to examine the surface chemistry of the passive film as a function of applied potential for Al,Al-Ta, and Al-Zr alloys. The passive film that forms on each alloy becomes enriched in oxidized solute as the specimen is anodically polarized. In general, the oxidized solute protects the substrate by restricting the ingress of chloride and oxygen and thereby preventing or reducing localized attack and film growth, respectively. Of the solutes examined to date, Ta is the most effective in this regard; the passive film on A1-Ta alloys remains thin and protective at the most noble potentials. Breakdown occurs only as the potential drop across the film becomes great enough to allow the transport of chlorides.

• Research Organization: Martin Marietta Labs., Baltimore, MD (USA)
• OSTI ID: 5931309
• Report Number(s): AD-A-204742/1/XAB; MML-TR-89-12C
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ELECTROCHEMICAL CORROSION
ALUMINIUM ALLOYS
CHLORIDES
CORROSIVE EFFECTS
TANTALUM ALLOYS
ZIRCONIUM ALLOYS
CHEMISTRY
FILMS
OXIDATION
OXYGEN
PHOTOELECTRON SPECTROSCOPY
PROGRESS REPORT
SOLUTES
SUBSTRATES
SURFACES
ALLOYS
CHEMICAL REACTIONS
CHLORINE COMPOUNDS
CORROSION
DOCUMENT TYPES
ELECTRON SPECTROSCOPY
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
METALS
NONMETALS
SPECTROSCOPY
360105* - Metals & Alloys- Corrosion & Erosion