Microstructure and transformation related behaviors of a Ni45.3Ti29.7Hf20Cu5 high temperature shape memory alloy

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Karaca H. E., Acar E., Ded G. S., Saghaian S. M., Basaran B., Tobe H., ...More

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, vol.627, pp.82-94, 2015 (SCI-Expanded)

• Publication Type: Article / Article
• Volume: 627
• Publication Date: 2015
• Doi Number: 10.1016/j.msea.2014.12.111
• Journal Name: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
• Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
• Page Numbers: pp.82-94
• Keywords: NiTiHfCu alloys, Phase transformation, TWSME, Shape memory effect, Shape memory alloys, NITIHFPD SINGLE-CRYSTALS, INDUCED MARTENSITIC-TRANSFORMATION, COMPRESSIVE RESPONSE, HF ALLOYS, AL ALLOY, PHASE, DEFORMATION, HYSTERESIS, DEPENDENCE, STRENGTH
• Erciyes University Affiliated: Yes

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 Us 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 degrees C under high compressive stresses (700 MPa) 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. (C) 2015 Elsevier B.V. All rights reserved.