Abstract
In this study, by conducting cryogenic rolling (CR) followed by short-term annealing (CRA), we achieved the annealing-induced hardening in a single-phase FCC FeCoCrNiMo0.2 high-entropy alloy by introducing multiple heterostructures structures. Through this approach, the yield strength, ultimate tensile strength and tensile fracture elongation of CRA alloy were increased from 1116.8 MPa to 1286.1 MPa, 1363.2 MPa to 1576.3 MPa and 5.4–6.9 %, respectively. Furthermore, a broader steady state of strain softening behavior was found in the CRA alloy, which is attributed to the additional strengthening and hardening effects resulting from high density of deformation nanotwins and phase transformations. Additionally, the research results show that the ultra-high strength and sufficient ductility of CRA alloy are attributed to the synergistic effect of multiple mechanisms, such as strengthening induced by heterogeneous microstructure of σ precipitate/HCP phase/FCC matrix phase, and high work hardening ability caused by the heterogeneity of high density deformation nanotwins, geometrically necessary dislocations (GND), stacking faults (SFs) and Lomer-Cottrell locks (L-C locks) nano-scale defects. This work provides useful insights for alloys that involves multiple heterogeneous microstructures strengthening and provides a promising approach for the design and manufacture of high-strength structural materials.
Published Version
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