Corrosion of fully-annealed pure aluminum and a continuous-cast AA2037 aluminum alloy (solutionized and water quenched) in a 1M NaOH solution for various periods of time were analyzed with positron beam-based Doppler broadening spectroscopy. By varying the energy of the incident positron beam, corrosion-induced defects at different depths from the surface were detected. It was found that the Doppler-broadened annihilation line-width parameter was significantly increased near the surface of pure aluminum after corrosion, probably due to the interaction between positrons and nanometer-sized voids formed near the aluminum surface during corrosion. Examination by atomic force microscopy indicated that many pits were formed on the aluminum surface after corrosion. In contrast, a significant decrease in the linewidth parameter was observed in AA2037 alloy after corrosion and interpreted as being caused by copper enrichment at the metal-oxide interface during corrosion; such enrichment at large cavity sites was confirmed by energy dispersion spectrometry.
|Number of pages||9|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|State||Published - Aug 2012|
Bibliographical noteFunding Information:
This research is supported by the National Natural Science Foundation of China under grants 10975110, 51071111 and 11175136, and by the State Key Laboratory of Solidification Processing in NWPU under Grant No. SKLSP201004. One of the authors (TZ) was sponsored by the US NSF through a Career Award (Grant No. DMR-0645246).
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys