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Proceedings Paper

Effects of heat treatment on shape-setting and non-linear mechanical properties of Nitinol stent
Author(s): Xiaopeng Liu; Yinong Wang; Min Qi; Dazhi Yang
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Paper Abstract

NiTi shape memory alloy is a temperature sensitive material with non-linear mechanical properties and good biocompatibility, which can be used for medical devices such as stent, catheter guide wire and orthodontic wire. The majority of nitinol stents are of the self-expanding type basing on the superelasticity. Nitinol stents are shape set into the open condition and compressed and inserted into the delivery catheter. Additional the shape-setting treatment can be used as a tool to accurately tune the transformation temperatures and mechanical properties. In this study, different heat treatments have been performed on the Ti-50.7at%Ni alloy wires. And results of shape-setting, austenite transformation finish temperature and non-linear mechanical property of NiTi shape memory alloy at body temperature have been investigated. The experimental results show that the proper shape-setting temperature should be chosen between 450-550 °C. And the shape-setting results were stabilization when the NiTi wires were constrain-treated at 500 and 550°C and ageing time longer than 10 minutes. The austenite finish temperatures increased with ageing time and increased first and then decreased with ageing temperature. The peak values were obtained at 400°C. When the heat treatments was performed at the same temperature, both the upper plateau stresses and lower plateau stresses decreased with the ageing time. Most of treated nitinol wires owned good recovery ability at body temperature and the permanent sets were less than 0.05% when short time ageing treatment was performed at 500°C.

Paper Details

Date Published: 1 November 2007
PDF: 7 pages
Proc. SPIE 6423, International Conference on Smart Materials and Nanotechnology in Engineering, 64233N (1 November 2007); doi: 10.1117/12.779395
Show Author Affiliations
Xiaopeng Liu, Dalian Univ. of Technology (China)
Yinong Wang, Dalian Univ. of Technology (China)
Min Qi, Dalian Univ. of Technology (China)
Dazhi Yang, Dalian Univ. of Technology (China)


Published in SPIE Proceedings Vol. 6423:
International Conference on Smart Materials and Nanotechnology in Engineering

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