Abstract
In this study,the deformation behaviors and related microstructural evolutions were investigated in ei-ther monotonic or cyclic deformation modes in an interstitial metastable high-entropy alloy.These inves-tigations aimed to reveal the mechanisms underlying the superior low-cycle fatigue(LCF)life of this alloy.A thermomechanical process was applied to induce fine-grained(FG)and coarse-grained(CG)microstruc-tures in Fe-30Mn-10Co-1OCr-0.4C(atomic percentage)alloy.Their superior combination of strength and ductility was attributed to the appearance of deformation-induced ε-martensite and the presence of car-bon.The CG alloy showed a greater volume fraction of ε-martensite than the FG alloy in the monotonic deformation mode,and vice versa in the cyclic mode.Such a disparity was interpreted in light of the back-stress effect of the relaxed y-grain boundaries in the latter mode.Meanwhile,the γ-to-ε phase transformation under cyclic loading at low strain amplitudes(0.4％)barely led to an improved fatigue life as compared with that at higher strain amplitudes(≥0.55％).The high reversibility of partial disloca-tion motions under cyclic loading and delaying the formation of dislocation cells through the martensitic transformation could explain why the alloys investigated in this study exhibited a superior LCF life com-pared with high-entropy alloys reported in previous studies.
基金项目
National Research Foundation of Ko-rea(NRF)grant funded by the the Ministry of Science and ICT(MSIT,Korea)(2021R1A2C1095139)
NETL
NSTL
维普
万方数据