Tuning needle-like precipitation for enhanced strength-ductility synergy in a non-equiatomic FeNiCoCuTi high-entropy alloy

• A novel non-equiatomic Fe27Ni27Co26Cu10Ti10 HEA was developed, achieving a fcc+η structure after heat treatment, with total elongation improved from ~0.9% to 7.5%. • The needle-like η-D024 phase, often considered deleterious, was shown to provide effective precipitation strengthening while maintaining ductility, expanding reinforcing phase options for fcc HEAs. • The enhanced ductility is attributed to the strong hindering effect of needle-like η phase at grain boundaries, restricting crack propagation and dislocation movement. • This study provides valuable insights into phase transformation and the strengthening effect of the η-D024 phase, guiding future alloy design for strength-ductility synergy.