Microstructural design and deformation behavior of a TRIP/TWIP tri-phase heterogeneous high-entropy alloy

In this study, a tri-phase heterogeneous high-entropy alloy (HEA) (Al9(Fe50Mn30Co10Cr10)91, at. %) exhibiting transformation- and twinning-induced plasticity (TRIP-TWIP) that overcomes the strength-ductility trade-off. The current HEA was systematically investigated the microstructure and mechanical properties under different thermo-mechanical processing (TMP). The HEA had a hierarchical microstructure of face-centered cubic (FCC), body-centered cubic (BCC), and a small content of hexagonal close-packed (HCP) phases after TMP. As regards the mechanical properties, after introducing recrystallized zone of -14.5 vol%, the HEA showed a strength of 1.15 GPa with total elongation of 10%. When the recrystallized fraction increased to -69.9 vol%, the HEA exhibited a combination of yield strength -489 MPa and tensile strength -704 MPa, while a satisfactory uniform elongation of 37% was maintained. The deformation activated multiple strengthening mechanisms, including dislocation slip, stacking faults, TRIP-TWIP effects, etc. led to a significant increase of work hardening rate in the intermediate stage of the strain. Additionally, the phase distribution and recrystallized grains morphology were characterized and the relationship between their results and the strength-ductility synergy were discussed. These findings provide a new method to tune the mechanical behavior of HEAs.

Automated summary

This study systematically investigated the microstructure and mechanical properties of a tri-phase heterogeneous high-entropy alloy (HEA) under different thermo-mechanical processing. The HEA exhibited a hierarchical microstructure and showed varying mechanical properties depending on the recrystallized fraction. Multiple strengthening mechanisms were activated during deformation, leading to an increase in work hardening rate. The phase distribution and recrystallized grains morphology were characterized, providing insights into the synergy between strength and ductility in HEAs.