Grain Boundary Segregation and Stress Corrosion Cracking of Aluminum Alloys
Abstract
Auger electron spectroscopy and chemical depth profiling by argon sputtering were employed to obtain the grain boundary segregation profiles of various aluminum alloys. Samples of both commercial (7075, 7050, and 7049) and high purity alloys based on the Al-Zn-Mg ternary in different heat treatments were examined following in situ fracturing in the spectrometer. Segregation profiles indicate that the grain boundaries in these alloys are considerably enriched in Mg and Zn. In commercial alloys, however, the grain boundaries are depleted in the minor elements Fe, Cu and Si. AES spectra of oxide films formed on Al-Zn-Mg alloys indicate that the enhanced segregation along the grain boundaries results in a film rich in Mg. It is postulated that incorporation of extensive amounts of these alloying elements into the film renders it less protective and leads to enhanced hydrogen entry and embrittlement by stress corrosion cracking.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1976
- Accession Number
- ADA033096
Entities
People
- J. A. Green
- R. K. Viswanadham
- T. S. Sun
- W. G. Montague
Organizations
- Martin Marietta