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

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外文摘要：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.

外文关键词：

High-entropy alloyNanotwinsFatigueImpact behaviorAdditive manufacturing

作者：

Guoqing Huang、Bo Li、Yinan Chen、Fuzhen Xuan

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作者单位：

School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China

Additive Manufacturing and Intelligent Equipment Research Institute,East China University of Science and Technology,Shanghai 200237,China

Shanghai Collaborative Innovation Center for High-end Equipment Reliability,Shanghai 200237,China

基金：

National Natural science Foundation of ChinaNational Key R&D Program of ChinaFundamental Research Funds for the Central Universities in ChinaPre research project of Civil Aerospace TechnologyEquipment Preresearch Sharing Technology Key Project

项目编号：

521751402022YFB4602102JKG01231610D020301JZX7Y20210422004601

出版年：

2024

DOI：

10.1016/j.jmst.2023.10.028

材料科学技术(英文版)

中国金属学会中国材料研究学会中国科学院金属研究所

材料科学技术(英文版)

CSTPCD

影响因子：0.657

ISSN：1005-0302

年,卷(期)：2024.183(16)