Nanotwining induced by tensile fatigue and dynamic impact of laser powder bed fusion additively manufactured CoCrFeNi high-entropy alloy  

作　　者：Guoqing Huang Bo Li Yinan Chen Fuzhen Xuan 

机构地区：[1]School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China [2]Additive Manufacturing and Intelligent Equipment Research Institute,East China University of Science and Technology,Shanghai 200237,China [3]Shanghai Collaborative Innovation Center for High-end Equipment Reliability,Shanghai 200237,China

出　　处：《Journal of Materials Science & Technology》2024年第16期241-257,共17页材料科学技术（英文版）

基　　金：sponsored by the National Natural Science Foundation of China(Grant No.52175140);National Key R&D Program of China(Grant No.2022YFB4602102);Fundamental Research Funds for the Central Universities in China(Grant No.JKG01231610);Pre research project of Civil Aerospace Technology(Grant No.D020301);Equipment Pre-research Sharing Technology Key Project(Grant No.JZX7Y20210422004601).

摘　　要：The laser powder bed fusion(L-PBF)additively manufactured CoCrFeNi high-entropy alloy(HEA),with face-centered cubic(FCC)crystal structure,demonstrates better comprehensive mechanical properties in the building direction(BD).Loading quasi-static,dynamic fatigue,and dynamic separated Hopkinson press bar(SHPB)impact stress conditions along the BD of the L-PBF processed HEA exhibit intriguing mi-crostructural evolution characteristics.The L-PBF generates hierarchical dislocation grids containing nu-merous cell substructures within the HEA FCC grains,impeding dislocation motion during deformation and improving the strength.When subjected to dynamic fatigue loading,the dislocation grids restrict the mean free path of dislocations and thus trigger the activation of abundant stacking faults.Hence,nu-merous nanotwins form near the end of the fatigue life.Multiple twinning systems can also be activated under dynamic high-speed impact loading.Especially at a low temperature of 77 K,the stacking fault energy of the CoCrFeNi HEA decreases,resulting in increased activation of nanotwins,exhibiting excep-tional toughness and resistance to dynamic loads.Additional twin boundaries also impede dislocation movement for the strain hardening.These findings hold valuable implications for the study of additively manufactured HEA parts working in extreme environments.

关 键 词：High-entropy alloy NANOTWINS FATIGUE Impact behavior Additive manufacturing 

分 类 号：TG132.3[一般工业技术—材料科学与工程] TG665[金属学及工艺—合金]