Abstract
Precipitation-strengthened medium/high-entropy alloys(MEAs/HEAs)have great potential for high-temperature applications.In this study,we designed a novel Ni45.9Fe23Cr23V4Nb3Mo1B0.1(at.％)MEA alloy,hardened by the D022(Ni,Fe,Cr)3(Nb,V)-type nanoprecipitates,with an excellent strength-ductility com-bination from room to elevated temperatures.Specifically,the tensile strengths,at 700 and 800 ℃,could be maintained as high as 845 and 589 MPa,respectively;meanwhile,elongations at all testing temper-atures 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 crit-ical resolved shear stress(CRSS)to initiate SFs in both face-centered cubic(FCC)and D022 phases was evaluated,and the possible reasons for the origin of anomalous DTs at 800 ℃ were discussed in de-tail.The main findings demonstrate that the shearable D022 nanoparticles can provide the FCC matrix with considerable dislocation storage capacity,reinforcing strain hardening at ambient and intermedi-ate temperatures.This work provides fundamental insights into the controllable design and deformation mechanisms of high-performance D022-strengthened MEAs/HEAs.
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