Observations of grain-boundary sliding and surface topography in an 8090 Al alloy after uniaxial and biaxial superplastic deformation

Journal Article · Fri Jan 01 04:00:00 EST 1999 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-999-0195-5· OSTI ID:316069

Chen, T R; Huang, J C ^[1]

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1. National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China). Inst. of Materials Science and Engineering

The surface topography of an 8090 aluminum alloy was studied after uniaxial or biaxial superplastic deformation, with particular reference to grain-boundary sliding (GBS) offsets, grain rotation angles, formation of striated bands (SBs) or fibers, cavity distribution, and cavity formation mechanisms. Additionally, the contribution of GBS or grain separation to the overall strain was evaluated. Striated bands were observed and are thought to be the newly exposed faces of the grains inclined to the specimen`s surface. They were formed by sliding of grains upward and downward relative to the specimen surface. Grooves and crests inside SBs were formed from the relative motion of grain-boundary defects. Fibers were observed and are thought to be the further development of the SBs resulting from the formation of elongated cavities and grain separation. More cavitation was found in equibiaxially strained regions than in other regions subjected to approximately equivalent levels of strain. About 50 pct of the total strain was contributed to GBS in the uniaxial tensile-loaded specimens, as compared to about 30 pct in the biaxial-strained specimens. The effects of grain separation, grain rotation, and secondary GBS may be the reasons for the reduction of the observed strain contribution from GBS in biaxially strained specimens.

• Sponsoring Organization: USDOE
• OSTI ID: 316069
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 1 Vol. 30; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
CAVITIES
DEFORMATION
FIBERS
GRAIN BOUNDARIES
PLASTICITY
STRAINS
STRIATIONS
TEXTURE