A novel D022-strengthened medium entropy alloy with outstanding strength-ductility synergies over ambient and intermediate temperatures.

• A CALPHAD-aided strategy is implemented to design a high-performance Ni 45.9 Fe 23 Cr 23 V 4 Nb 3 Mo 1 B 0.1 (at.%) medium entropy alloy strengthened by D0 22 nanoparticles. • The newly designed alloy exhibits excellent mechanical properties at both room and intermediate temperatures, with ultimate tensile strength and fracture elongation of ∼845 MPa and 27.5 % at 700 °C, respectively, and ∼589 MPa and 24.3 % at 800 °C, respectively. • The superior combination of strength and ductility over a wide temperature range is primarily attributed to the high-density interactions of planar dislocation configurations (mainly stacking faults) and the shearable D0 22 nanoparticles. • Anomalous deformation twinning at 800 °C can be activated due to the localized stress concentration, the locally low stacking-fault energy, and especially the high diffusion rate at grain boundaries. Precipitation-strengthened medium/high-entropy alloys (MEAs/HEAs) have great potential for high-temperature applications. In this study, we designed a novel Ni 45.9 Fe 23 Cr 23 V 4 Nb 3 Mo 1 B 0.1 (at.%) MEA alloy, hardened by the D0 22 (Ni, Fe, Cr) 3 (Nb, V)-type nanoprecipitates, with an excellent strength-ductility combination from room to elevated temperatures. Specifically, the tensile strengths, at 700 and 800 °C, could be maintained as high as 845 and 589 MPa, respectively; meanwhile, elongations at all testing temperatures exceeded 25 % without any intermediate-temperature embrittlement. The temperature-dependent deformation mechanisms were unraveled using multi-scale characterizations, which involved profound slip planarities, such as stacking fault (SF) networks and deformation twins (DTs). Furthermore, the critical resolved shear stress (CRSS) to initiate SFs in both face-centered cubic (FCC) and D0 22 phases was evaluated, and the possible reasons for the origin of anomalous DTs at 800 °C were discussed in detail. The main findings demonstrate that the shearable D0 22 nanoparticles can provide the FCC matrix with considerable dislocation storage capacity, reinforcing strain hardening at ambient and intermediate temperatures. This work provides fundamental insights into the controllable design and deformation mechanisms of high-performance D0 22 -strengthened MEAs/HEAs. [Display omitted] [ABSTRACT FROM AUTHOR]