A comprehensive overview of shape memory alloys: Recent advances in fabrications, properties, and applications for next-generation smart systems

Shape Memory Alloys (SMAs) are a class of smart materials that can recover their original shape through reversible martensitic phase transformations triggered by thermal or mechanical stimuli. This review synthesizes recent advancements in SMA research, focusing on underlying mechanisms, alloy systems (NiTi, Cu-, and Fe-based), fabrication techniques such as casting, powder metallurgy, additive manufacturing, and advanced machining. Post-processing methods including thermal aging, rolling, and thermomechanical training are explored for their effects on phase transformation, fatigue life, and superelastic behavior. Molecular dynamics simulations are discussed as a powerful tool for probing nanoscale thermo-mechanical performance. Applications across biomedical, aerospace, automotive, and structural sectors are critically discussed, highlighting the potential of SMAs in adaptive and energy-efficient systems. Finally, current challenges and emerging opportunities are outlined, providing a forward-looking perspective for the design, processing, and deployment of next-generation SMAs in advanced engineering applications.