Experimental Characterization of Shape Memory Alloys

Characterization of the microstructure and shape memory behavior of shape memory alloys (SMAs) is an essential part of understanding and modeling the behavior of these alloys. This chapter focuses on the methods and procedures to determine the shape memory properties. Transformation temperatures (TTs) are some of the most important shape memory properties. Shape memory properties are highly microstructure dependent, so it is crucial to determine the microstructural features of SMAs. The chapter discusses shape memory effect and superelasticity tests. It briefly introduces effects of aging, crystal structure, orientation, and cycling on the shape memory behavior. The chapter explains important parameters and methods for their measurement such as recoverable and irrecoverable strains, critical stress for transformation, and hysteresis of SMAs. It also discusses Vickers hardness test procedure, indentation methods, and microstructural characterization by the optical microscopy and X-ray diffraction (XRD) method.