Interaction between martensitic transformations and defects during thermal and pseudoelastic cycling in CuAlNi single crystals, pp. 145-180
Authors: R. Gastien, M. Sade and F. C. Lovey
Abstract: CuAlNi shape memory materials are promising for high temperature technological applications over other Cu based alloys, as they show low diffusion at temperatures close to room temperature or higher [1, 2]. For the development of actuator devices using CuAlNi alloys, it is necessary to study the thermal and mechanical response of the material due to cycling through the martensitic transformation. Additionally, the use of a single crystal material increases the life to fracture, and finally enhances the performance of future devices based on these materials. In some CuAlNi alloys, a metastable β-bcc ordered structure obtained at room temperature can undergo martensitic transformations by cooling or applying stress (σ). Three types of martensitic transformations can be induced for chemical compositions between 13-15Al and 0-6Ni (wt.%): β↔γ’, β↔β’ and β↔β’+γ’. In this chapter, the authors review the more recent research made on thermal and pseudoelastic tensile cycling in CuAlNi single crystals, and the interaction between martensitic transformations and defects which causes a novel effect in these alloys.