| Issue |
J. Phys. IV France
Volume 05, Number C8, Décembre 1995
International Conference on Martensitic Transformations – ICOMAT 95
|
|
|---|---|---|
| Page(s) | C8-593 - C8-598 | |
| DOI | https://doi.org/10.1051/jp4/199558593 | |
| Published online | 14 juillet 2014 | |
Influence of Elastic Energy on the Unloading Behaviour of NiTi Shape Memory Alloys
1
Department of Mechanical and Materials Engineering, University of Western Australia, Nedlands, WA 6907, Australia
2
Laboratoire Sols Solides Structures, Université Joseph Fourier, BP. 53X, 38041 Grenoble cedex, France
Abstract
A non-linear unloading path of deformed NiTi shape memory alloys was observed during mechanical testing at various temperatures, giving a strain recovery larger than what expected from elasticity. Whilst the nonlinear unloading path at above the As temperature may be rationalised by a simultaneous reverse transformation from the oriented martensite to austenite, the non-linear strain recovery during unloading at below the As temperature must have a different mechanism, because the thermodynamic driving force for a reverse transformation is negative. This second mechanism is ascribed to a 'self-deorientation' process of the fully oriented martensite and the driving force for this process is attributed to the elastic energy stored in the matrix during the forward deformation process.
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