Research and Development in NiTi Shape Memory Alloys Fabricated by Selective Laser Melting

The postprocessing/machining of NiTi shape memory alloys (SMAs) is extremely challenging and difficult due to their low thermal conductivity and the high reactivity of ready-made NiTi parts. As a typical metal additive manufacturing technology, selective laser melting (SLM) offers significant advantages and can directly fabricate complex metallic parts, effectively address the problems of cold workability and machinability for NiTi parts. By establishing the relationship between processing parameters, microstructure, functional properties, and revealing the underlying mechanisms for altered phase transformation behavior and functional properties of SLM NiTi SMAs, it can serve as a theoretical foundation for expanding the applications of SLM NiTi SMAs. As a result, this paper comprehensively evaluates the formability, phase transformation behavior, microstructure, mechanical properties, and thermomechanical properties of SLM NiTi SMAs. Additionally, the design of SLM porous NiTi SMAs, as well as their biocompatibility, are discussed. Eventually, the future development trend and critical problems in studying SLM NiTi SMAs are investigated.