Influence of the Structure on the Strain-Controlled Fatigue of Nitinol

Abstract:

The influence of increased dislocation density; dispersity of Ni-rich (Ti₃Ni₄ and Ti₂Ni₃) particles and volume fraction of Ti-rich (Ti₂Ni) particles on the low-cycle (high amplitude) and high-cycle (low amplitude) fatigue resistance of nitinol has been considered in this paper. It was revealed that the fatigue resistance of nitinol in low-cycle conditions may be improved by increasing the part of deformation which is realized by martensitic mechanism. This part may be estimated by measuring ε_cr, which can reflect the influence of the structure parameter both on σ_M and σ_slip. It was found that in high-cycle fatigue conditions the substructure of nitinol predominantly determine its fatigue resistance, which is being the better in samples that had higher dislocation density or high dispersity of Ni-rich particles (up to 30 nm).

• Periodical: Materials Science Forum (Volumes 738-739)
• Pages: 316-320
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.738-739.316
• Online since: January 2013
• Authors: Mikhail Kollerov, Elena Lukina, Dmitiy Gusev, Peter Mason, Paul Wagstaff
• Keywords: Fatigue, NiTi, Nitinol, Strain, Structure

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