Flow behavior and microstructure of Co{sub 3}Ti intermetallic alloy during superplastic deformation

Journal Article · Fri Jun 12 04:00:00 EDT 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00029-9· OSTI ID:638321

Kim, W Y; Hanada, S; Takasugi, T ^[1]

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1. Tohoku Univ., Sendai (Japan). Inst. for Materials Research

The superplastic deformation of the L1{sub 2}-type Co{sub 3}Ti alloy was observed as functions of temperature, strain rate and initial grain size, and then characterized by the flow behavior, the constitutive equation and the deformation microstructure. In the region of higher strain rate (also lower temperature and larger initial grain size), the flow curve exhibited a stress peak followed by a rapid stress decrease, and dynamic recrystallization (DRX) occurred. The activation energy of deformation in this region was estimated to be Q = 158 kJ/mol, similar to that for the bulk diffusion. It is suggested that the mechanism associated with DRX is responsible for the deformation in this region. In the region of lower strain rate, (also higher temperature and smaller initial grain size), the flow curve exhibited continuous work hardening until fracture, and the concomitant motion of grain boundary sliding and grain growth occurred. The activation energy of deformation in this region was estimated to be Q = 80 kJ/mol suggestive of that of grain boundary diffusion. Large tensile elongation, i.e., superplastic deformation beyond 200% was observed in the latter region. It is suggested that the grain boundary sliding-based mechanism is responsible for the deformation in this region.

• OSTI ID: 638321
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 10 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
COBALT ALLOYS
GRAIN SIZE
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
PLASTICITY
STRAIN RATE
TEMPERATURE DEPENDENCE
TITANIUM ALLOYS