Статья

Microstructural origins of high strength and high ductility in an AlCoCrFeNi2.1 eutectic high-entropy alloy

Xuzhou GaoNano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, ChinaYiping LuKey Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Engineering, Dalian University of Technology, Dalian, 116024, ChinaBo ZhangHerbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing, 210094, ChinaNingning LiangNano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, ChinaGuanzhong WuNano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, ChinaGang ShaHerbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing, 210094, ChinaJizi LiuHerbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing, 210094, ChinaYonghao ZhaoNano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China

2017en

ABI

Аннотация

Recent studies indicate that eutectic high-entropy alloys can simultaneously possess high strength and high ductility, which have potential applications in industrial fields. Nevertheless, microstructural origins of the excellent strength–ductility combination remain unclear. In this study, an AlCoCrFeNi2.1 eutectic high-entropy alloy was prepared with face-centered cubic (FCC)(L12)/body-centered-cubic (BCC)(B2) modulated lamellar structures and a remarkable combination of ultimate tensile strength (1351 MPa) and ductility (15.4%) using the classical casting technique. Post-deformation transmission electron microscopy revealed that the FCC(L12) phase was deformed in a matter of planar dislocation slip, with a slip system of {111} <110>, and stacking faults due to low stacking fault energy. Due to extreme solute drag, high densities of dislocations are distributed homogeneously at {111} slip plane. In the BCC(B2) phase, some dislocations exist on two {110} slip bands. The atom probe tomography analysis revealed a high density of Cr-enriched nano-precipitates, which strengthened the BCC(B2) phase by Orowan mechanisms. Fracture surface observation revealed a ductile fracture in the FCC(L12) phase and a brittle-like fracture in the BCC(B2) lamella. The underlying mechanism for the high strength and high ductility of AlCoCrFeNi2.1 eutectic high-entropy alloy was finally analyzed based on the coupling between the ductile FCC(L12) and brittle BCC(B2) phases.

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Идентификаторы

DOI: 10.1016/j.actamat.2017.07.041

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