Advancing engineering frontiers with NiTi shape memory alloys: A multifaceted review of properties, fabrication, and application potentials

This study provides a comprehensive review of the observation of NiTi Shape Memory Alloys (SMAs) in engineering applications and beyond. The study encompasses experimental observations on the physical, mechanical, microstructural, and crystallographic aspects of NiTi SMAs, as well as discussions on fabrication techniques and failure analysis, all in relation to the opportunities they offer in engineering applications. Through a comparative analysis of NiTi, the Shape Memory Effect (SME) was examined considering its unique properties and composition within various engineering contexts. The investigation further delves into the influences of microstructure, composition, formation, and cyclic application on the behaviour of NiTi. Key findings revealed that while SME effects are evident, heat flow gradients may experience slight alterations, and an increased number of cycles might impact the recovery factor. Additionally, the heat flow gradient plots undergo changes during heat treatment, corresponding to variations in the NiTi crystal structure. Also, SME is observable at both low and high temperatures, and it can be augmented by blending NiTi with other alloys to enhance mechanical and microstructural properties. At the microstructural level, NiTi may exhibit differences in unrecoverable strain between the R-phase and B2-phase. Fabrication and joining processes pose challenges such as loss of SME, machining difficulties, weld strength, burr formation, grain sensitivity and dissimilar joining challenges, but these hurdles are outweighed by the multitude of opportunities they present for advanced engineering applications. As the demand for smart materials and innovative engineering solutions grows, the study firmly establishes the practicality and efficacy of NiTi SMA prospects.