Extraordinary strength-ductility synergy in chemically complex intermetallic alloys with hierarchical dual-phase nanostructures
Weicheng Xiao, Weiwei Xu, J.X. Zhang, Jinyong Zhang, Shaofei Liu, Bo Xiao, Yinghao Zhou, Jiang Ju, Qing Li, Yushun Zhao, Xun‐Li Wang, Peter K. Liaw, Tao Yang
Abstract
Developing structural materials with an excellent combination of strength and ductility is a parament task in advanced industries. Conventional intermetallic alloys (IMAs) usually suffer from insufficient ductility, which severely restricts their practical applications. In this study, we developed a novel high-performance bulk chemically complex intermetallic alloys (CCIMAs) in the multicomponent (Ni, Co) 3 (Si, Ti, Al) system. The microstructure, mechanical properties, and associated deformation behaviors were systematically investigated through combinational analyses such as three-dimensional atom probe tomography (3D-APT) and transmission electron microscope (TEM). By multi-step cold rolling and annealing path, the newly developed (Ni, Co) 3 (Si, Ti, Al)-type alloys show a unique hierarchical dual-phase nanostructure, exhibiting extraordinary strength and ductility at ambient temperature. The yield strength, tensile strength, and ductility can reach ∼1011 MPa, ∼1690 MPa, and 35 %, respectively. Detailed TEM and 3D-APT analyses revealed that the coherent Co-rich disordered nanoparticles precipitated out from the L1 2 matrix region. These reversely precipitated nanoparticles are mainly sheared by superlattice dislocation pairs and generate a significant strengthening effect. Superlattice stacking faults (SSFs) were also observed at large deformation due to the reduction of stacking fault energy and high stress level that reaches a critical value. These findings are expected to accelerate the innovative design of ultra-strong yet ductile intermetallic compounds for structural applications.