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Updated: Jun 3, 2026
05:04
Determining the Mechanical Strength of Ultra-Fine-Grained Metals
Published on: November 22, 2021
Deformation twinning in a creep-deformed nanolaminate structure
1Lawrence Livermore National Laboratory, Physical and Life Sciences Directorate, L-352, PO Box 808, Livermore, CA 94551-9900, USA. hsiungl@llnl.gov
Summary
Deformation twinning in TiAl-(γ)/Ti(3)Al-(α(2)) nanolaminates at high temperatures is driven by interface sliding. Interfacial dislocation pile-ups trigger twinning, offering an alternative to limited lattice dislocation movement for accommodating creep strains.
Area of Science:
- Materials Science
- Mechanical Engineering
- Metallurgy
Background:
- Deformation twinning is crucial for material plasticity.
- Nanolaminate structures present unique deformation mechanisms.
- High-temperature creep behavior in TiAl alloys is complex.
Purpose of the Study:
- To elucidate the mechanism of deformation twinning in TiAl-(γ)/Ti(3)Al-(α(2)) nanolaminates under creep conditions.
- To investigate the role of lattice and interfacial dislocations in high-temperature deformation.
- To propose a novel interface-controlled twinning mechanism.
Main Methods:
- Analysis of creep deformation at elevated temperatures.
- Investigation of lattice and interfacial dislocation behavior.
- Microstructural examination of deformation mechanisms.
Main Results:
- Limited lattice dislocation activity in γ and α(2) lamellae.
- Interface sliding emerges as a primary deformation mode.
- Pile-ups of interfacial dislocations act as precursors to twinning.
- A stress concentration from interfacial dislocation pile-ups drives twinning.
Conclusions:
- An interface-controlled twinning mechanism is proposed for TiAl-(γ)/Ti(3)Al-(α(2)) nanolaminates.
- Interface sliding and interfacial dislocations are key to high-temperature creep deformation.
- Deformation twinning accommodates creep strains when lattice dislocation flow is insufficient.
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