Abstract:Additive manufacturing technique provides a new approach for the fabrication of complex structures and precise control of the microstructure in high-entropy alloys (HEAs), greatly expanding their application prospects in extreme service environments such as aerospace and deep-space exploration. However, there is still a lack of systematic and in-depth understanding of the mechanical behavior of additively manufactured HEAs under cryogenic conditions, particularly regarding their dynamic impact response and underlying microstructural deformation mechanisms. In this study, a Ni40Co18Cr18Fe14Al5Ti5 HEA was prepared using selective laser melting (SLM), and its static tensile and dynamic impact mechanical behaviours at 77 K were investigated. The results show that this HEA exhibits excellent strength-ductility synergy and impact toughness at cryogenic temperature, with a yield strength of 1083.4 MPa, a uniform elongation of 29.8%, and an impact energy as high as 117.7 J. Microstructural analysis reveals that the high-density dislocations, stacking faults, and their interactions between the initial cellular structures during cryogenic deformation effectively facilitate energy dissipation, thereby endowing this HEA with excellent cryogenic impact toughness.