Micromechanical origin for the wide range of strength-ductility trade-off in metastable high entropy alloys†. (1st July 2023) - Lyu, Zongyang
Abstract: Through different annealing temperatures and times, it is reported here that interstitial metastable high entropy alloys (HEAs) can exhibit a wide range of strength-ductility trade-offs. The underlying mechanisms were investigated via in situ neutron diffraction, electron backscattered diffraction, and electron channel contrast imaging analyses. These techniques revealed that the phase transformation process could be tuned by various annealing processes, resulting in different degrees of load partitioning and sharing among different phases and grain families on the commensurate microstructural length scales. Therefore, the microstructures generated by thermal treatments and phase transformation from face-centered-cubic to hexagonal-close-packed phases could efficiently improve the ductility of the studied alloys. Graphical abstract: Extraordinary combinations of tensile strength, ductility, and strength/ductility product can be achieved by interstitial metastable high entropy alloys (HEAs). In situ neutron diffraction measurements reveal different deformation mechanisms (e.g., interactions amongst dislocations, twins, and FCC-HCP phase transformation), which correlate nicely with the strength/ductility trends. Image, graphical abstract