Substitution of Ge for Mn increases the elastic moduli of different {h k l} orientations of the CoCrFeMnNi-based high-entropy alloy. Our findings indicate that tuning minor element compositions may result in improved strength-ductility combination. The underlying deformation mechanisms of CoCrFeNiGe 0.3 were examined by in situ neutron diffraction and analysis of the associated diffraction profiles during tensile deformation. The strain-hardening response of CoCrFeNiGe 0.3 exhibited a dominant mechanism of mechanical twinning at moderate and large strains at room temperature. The evolution of the bulk work hardening rate was consistent with the convolutional multiple whole profile fitting results, which exhibited a continuous increase in twin formation probability. The microstructural development was also investigated by transmission electron microscopy, which revealed the formation of huge amounts of deformation twins in CoCrFeNiGe 0.3 at room temperature.
Recently, novel high‐entropy alloys (HEAs) of Al–Co–Cr–Fe–Ni–Ti systems containing face‐centered cubic (FCC) matrix and γ′ precipitates (L12 phase) have been studied. They show superior mechanical properties at room (298 K) and cryogenic temperatures (77 K). Herein, microstructure deformation and fracture after tensile strain are investigated. The results show that multiple‐layered stacking faults occur after the tensile test at 77 K, which can increase the yield strength and ultimate tensile strength by 20% and 24%, respectively. The γ′ precipitates become disordered after the alloy deforms at 77 K, which decreases the formation barrier of mechanical twinning and increases ductility at 77 K by 27%.
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