Abstract
Effects of heat treatment temperature and time on the microstructure and shape memory behaviors (e.g. transformation temperatures, load-biased shape memory effect, superelasticity, two-way shape memory effect, and related properties) were investigated in a Ni45.3Ti29.7Hf20Cu5 (at%) high temperature polycrystalline shape memory alloy. Heat treatments could be used to control the TTs and to a lesser extent recoverable and irrecoverable strains. The Ni45.3Ti29.7Hf20Cu5 alloy was capable of recovering shape memory strains of up to 2% at temperatures above 100°C under high compressive stresses (700MPa) and up to 0.8% TWSME strain was possible after a non-intense stress-cycling training process. However, due to high Clausius-Clapeyron slopes, large temperature hysteresis, and a strong dependence of transformation stress on temperature, fully recoverable superelastic behavior was not observed because plastic deformation occurred concurrently with the stress-induced martensitic transformation.
Original language | English |
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Pages (from-to) | 82-94 |
Number of pages | 13 |
Journal | Materials Science and Engineering: A |
Volume | 627 |
DOIs | |
State | Published - Mar 1 2015 |
Bibliographical note
Publisher Copyright:© 2015 Elsevier B.V.
Keywords
- NiTiHfCu alloys
- Phase transformation
- Shape memory alloys
- Shape memory effect
- TWSME
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering