The role of dislocations in high-strain-rate superplasticity of an Al-Ni-misch metal alloy

Journal Article · Mon Aug 10 04:00:00 EDT 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00159-1· OSTI ID:651086

Umakoshi, Y; Fujitani, W; Nakano, T ^[1]; Inoue, A ^[2]; Ohtera, K ^[3]; Mukai, T ^[4]; Higashi, K ^[5]

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1. Osaka Univ., Suita, Osaka (Japan)
2. Tohoku Univ., Sendai (Japan). Inst. of Materials Research
3. Y.K.K. Kurobe, Toyama (Japan). Technical Research Labs.
4. Osaka Municipal Technical Research Inst. (Japan)
5. Osaka Prefecture Univ., Sakai, Osaka (Japan)

Plastic deformation, microstructure and deformation substructure in an Al-14 wt% Ni-14 wt% Mm (misch metal) alloy produced from amorphous powders were examined focusing on the effects of the initial average grain size d{sub 0}, the grain boundary sliding and the motion of dislocations on the superplasticity. The as-received and annealed specimens with d{sub 0} = 0.8, 1.6 and 1.5 {micro}m deformed at 873 K at an initial strain rate of 1/s. The specimen with d{sub 0} = 0.8 {micro}m showed high-strain-rate superplasticity accompanied by low flow stress and 350% elongation, while the flow stress increased and elongation deceased with greater grain size. Grain refinement occurred and the frequency of small angle boundaries showed a complicated change during superplastic deformation. On the other hand, in the specimen with d{sub 0} = 1.6 {micro}m, the grains coarsened rapidly. A large number of dislocations were observed in grains even in the superplastically deformed specimen. The high-strain-rate superplasticity of Al-14 wt% Ni-14 wt% Mm alloy is controlled by the grain boundary sliding but the motion of dislocations also plays an important role in accommodating the highly strained region near triple junctions of the grain boundaries.

• OSTI ID: 651086
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 13 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
DISLOCATIONS
ELONGATION
FLOW STRESS
GRAIN BOUNDARIES
MICROSTRUCTURE
MISCH METAL
NICKEL ALLOYS
PLASTICITY