Additive Manufacturing of NiTi Shape Memory Alloys for Elastocaloric Applications: A Review

Abstract

The elastocaloric (eC) effect, which harnesses the latent heat released during stress-induced transformations of superelastic shape memory alloys (SMAs), offers a promising pathway toward solid-state, environmentally friendly refrigeration technologies. However, the advancement of eC devices is constrained by the limited heat transfer surface area between SMAs and heat transfer fluids, as well as the high mechanical work input relative to the extracted latent heat. Among available SMAs, nickel titanium (NiTi) alloys are the most widely commercialized and exhibit strong potential for eC applications, yet their poor machinability and fabrication challenges hinder widespread implementation. Additive manufacturing (AM) provides a solution by enabling layer-by-layer fabrication of NiTi with complex geometries, thereby enhancing surface area and reducing work input through lattice structures. This review summarizes recent progress in AM-fabricated NiTi for eC applications, with an emphasis on components produced by laser powder bed fusion (LPBF) and directed energy deposition (DED) techniques using both wire and powder feedstocks. Finally, future directions and opportunities for integrating AM NiTi into practical eC devices are discussed.