Superelastic alloys for critical applications in extreme environments are required to combine a wide operating temperature range, low temperature sensitivity, and high strength. Achieving this combination is challenging. Drawing from high-entropy and superelastic alloy design principles, this study utilised laser-directed energy deposition (L-DED) to fabricate TiZrHfNiCu high-entropy superelastic alloys with excellent forming quality. The intricate composition and swift solidification conditions resulted in a uniform, fine, and isotropic dendritic microstructure within this high-entropy alloy, which comprises the B2 phase, B19’ phase, and Zr₂Cu-like phase. In comparison to the as-cast material, the LDED-TiZrHfNiCu material exhibits a reduced degree of component segregation and concurrently experiences strain glass transition alongside martensitic crystallisation behaviour. The alloy demonstrated recoverable superelastic strains exceeding 5%, a fracture strength over 2 GPa, and very low temperature sensitivity between 173 K and 473 K. Additionally, this method addresses the difficulties associated with machining superelastic alloys and the challenges associated with manufacturing complex geometries. This study illustrates the fabrication of TiZrHfNiCu alloy via L-DED, offering a new perspective on the preparation of high-strength, wide-temperature-range superelastic alloys and providing insights into phase-structure transformations and microstructural evolution in additively manufactured high-entropy superelastic alloys.

NiTiCu-based shape memory alloys have been considered as ideal materials for solid-state refrigeration due to their superb cycling stability for elastocaloric effect. However, the embrittlement and deterioration caused by secondary phase and coarse grains restrict their applications, and it is still challenging since the geometric components are required. Here, bulk NiTiCuCo parts with excellent forming quality were fabricated by laser powder bed fusion (LPBF) technique. The as-fabricated alloy exhibits refined three-phases hierarchical microcomposite formed based on the rapid cooling mode of LPBF, composed of intricate dendritic Ti₂Ni–NiTi composite and nano Ti₂Cu embedded inside the NiTi-matrix. This configuration endows far superior elastocaloric stability compared to the as-cast counterpart. The low fatigue stems from the strong elastic coupling between the interphases with reversible martensite transformation, revealed by in-situ synchrotron high-energy x-ray diffraction. The fabrication of NiTiCuCo alloy via LPBF fills the bill of complex geometric structures for elastocaloric NiTiCu alloys. The understanding of interphase micro-coupling could provide the guide for designing LPBF fabricated shape memory-based composites, enabling their applications for special demands on other functionalities.