Interfacial segregation and deformation of superplastically deformed Al-Mg-Mn alloys
Microstructural and microchemical studies have been carried out on superplastically deformed Al-Mg-Mn (AA5083-type) alloys. Grain boundary composition was measured using a Scanning Auger Microprobe (SAM) and an Analytical Transmission Electron Microscope (ATEM), while conventional TEM was used for microstructural evaluation. Non-equilibrium segregation of Si to grain boundaries following deformation was measured by both techniques. Significant interfacial Si enrichment was only detected in gage sections of tensile specimens after uniaxial strains from 50 to 200%. Grip regions which experience identical thermal histories, but without plastic deformation, did not reveal Si segregation. Selected samples also showed a slight depletion of Mg at grain boundaries after deformation. The only reproducible observation of equilibrium segregation was in Zr-modified alloys, where Sn was detected by SAM in both the deformed and undeformed sections of the sample. Microstructural analysis documented subgrain formation and subgrain-precipitate interactions during superplastic deformation. In addition, many grain boundaries and precipitate interfaces contained small (5 to 20 nm) voids. Compositional analysis of these nano-voids revealed that they were enriched in Mg with the adjacent boundary regions correspondingly depleted.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 40782
- Report Number(s):
- PNL-SA--26013; CONF-950201--13; ON: DE95009572
- Country of Publication:
- United States
- Language:
- English
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