Achieving excellent dynamic mechanical properties of additively manufactured FeCrNi medium-entropy alloy by cellular skeleton structure

Face-centered cubic (FCC) medium/high-entropy alloys (MEA/HEAs) exhibit high toughness and significant damage tolerance, making them highly promising for extreme engineering applications such as aerospace and defense that require materials to withstand high-speed dynamic loads. Nevertheless, the relatively low yield strength of FCC MEA/HEAs has limited their practical application. In this study, nanoscale NbC particles are successfully dispersed at the boundaries of the cellular structure through powder coating and laser-based powder bed fusion (PBF-LB/M), without requiring subsequent heat treatment. This approach yielded a novel FeCrNi MEA with a cellular skeleton structure decorated by dislocations, Nb/C element segregation, and NbC nanoparticles, demonstrating gigapascal-level yield strength over a wide range of strain rates. The high yield strength and strain rate sensitivity are mainly attributed to the strengthening effect of the cellular skeleton structure. During deformation, this structure restricts the movement of dislocations, twins, and stacking faults without completely immobilizing them, thereby enhancing mechanical performance. Additionally, the cellular skeleton structure exhibits excellent structural stability, preventing premature failure caused by stress concentration at the boundaries. The construction of the cellular skeleton structure significantly promotes the development of high-performance PBF-LB/M materials and provides an effective pathway for further enhancing alloy properties.