Dislocation model for continuous recrystallization during initial stage of superplastic deformation

Journal Article · Tue Feb 03 04:00:00 EST 1998 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(97)00535-6· OSTI ID:605678

Zhang, X; Tan, M J ^[1]

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1. Nanyang Technological Univ., Singapore (Singapore). School of Mechanical and Production Engineering

According to dislocation models, grain boundary sliding (GBS) causes stress concentrations when the sliding is impeded. Relaxation of the stress concentrations can be done by the emission of dislocations from one grain boundary to another. This process could be limited by the rate at which the dislocations are emitted (source control), or traverses the grains (glide or lattice climb control), or are absorbed into the boundaries (grain boundary climb control). The rate at which the grains slide past each other can be controlled by (1) the removal of a pile-up of lattice, the emission of lattice dislocations from grain boundary ledges and by the removal of pile-ups of grain boundary dislocations. These models require the grains to have high angle mobile boundaries such that grain boundary sliding processes can occur and are then accommodated by dislocation movements. For some quasi-single phase aluminum alloys, at the initial stage of superplastic deformation most of grain boundaries have low angles. Since movement of these subgrain boundaries needs very high energy, grain boundary sliding becomes difficult. It is widely reported that continuous recrystallization mechanism dominates the initial stage of superplastic deformation in quasi-single phase aluminum alloys.

• OSTI ID: 605678
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 5 Vol. 38; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
DISLOCATIONS
GRAIN BOUNDARIES
MATHEMATICAL MODELS
RECRYSTALLIZATION
SLIP
STRESS RELAXATION