Trends in the use of shape memory alloys in engineering and medicine | Mekhanika | kompozitsionnykh | materialov i konstruktsii
> Volume 23 > №2 / 2017 / Pages: 157-167

Trends in the use of shape memory alloys in engineering and medicine

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Shape memory alloys (SMA) consist of two or more components (austenitic, martensitic, rhombohedral, etc. phases) with significantly different mechanical properties (Young’s modulus of austenite and martensitic phases in titanium nickelide differ three-fold). Unlike conventional composites, in SMA the components can transform into each other with varying temperature and (or) stresses (thermoelastic martensitic phase transformations) or change the structure of some of the components under the action of stresses (structural transition). As a result, SMAs can accumulate or return deformations of a sufficiently large magnitude, i. e. managed way to change its shape. Therefore, SMA can be classified as a class of adaptive composites. Thanks to the phase and structural transitions occurring in the SMA, these materials have unique thermomechanical properties. They are characterized by such phenomena as the variability of elastic moduli in phase transitions, the accumulation of strains of direct transformation, monotonic, reversible and two way shape memory, martensitic inelasticity and superelasticity, oriented transformation, emanation and absorption of latent heat of phase transitions, dissipative phenomena. In this article are described: the experience in the use of the unique properties of shape memory alloys in single and cyclic actuators for aviation, medicine and safety systems in the oil and gas industry; prospects and challenges for the creation of adaptive aircraft structures, biocompatible implants and prostheses, thermal emergency valves.