Origin of superior low-cycle fatigue resistance of an interstitial metastable high-entropy alloy  

作　　者：Seyed Amir Arsalan Shams Jae Wung Bae Jae Nam Kim Hyoung Seop Kim Taekyung Lee Chong Soo Lee 

机构地区：[1]Graduate Institute of Ferrous Technology,Pohang University of Science and Technology,Pohang 37673,Republic of Korea [2]Department of Materials Science and Engineering,Pohang University of Science and Technology,Pohang 37673,Republic of Korea [3]School of Mechanical Engineering,Pusan National University,Busan 46241,Republic of Korea

出　　处：《Journal of Materials Science & Technology》2022年第20期115-128,共14页材料科学技术（英文版）

基　　金：the National Research Foundation of Korea(NRF)grant(Grant No.2021R1A2C1095139)funded by the the Ministry of Science and ICT(MSIT,Korea)。

摘　　要：In this study, the deformation behaviors and related microstructural evolutions were investigated in either monotonic or cyclic deformation modes in an interstitial metastable high-entropy alloy. These investigations 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) microstructures in Fe–30Mn–10Co–10Cr–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 carbon. 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 γ-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 dislocation 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 compared with high-entropy alloys reported in previous studies.

关 键 词：High-entropy alloy Transformation-induced plasticity Monotonic deformation Cyclic deformation Low-cycle fatigue Stacking faults 

分 类 号：TG139[一般工业技术—材料科学与工程]