Abstract
Eutectic high-entropy alloys,composed of FCC/B2 phases with a narrow solidification interval and excel-lent fluidity,have become a new hotspot in additive manufacturing.Nevertheless,their microstructures exhibit significant sensitivity to processing parameters,feedstocks,and composition,ultimately limiting the alloys'engineering applications.Here,a hypereutectic Ala.7CoCrFeNi2.4 alloy with a low cracking sus-ceptibility index was designed by Thermo-Calc calculation and fabricated by laser powder bed fusion.Results show that the as-printed Al0.7CoCrFeNi2.4 alloy manifests a stable cellular structure,coupled with appreciable ultimate tensile strength(≥1200 MPa)and ductility(≥20％)over a wide range of process-ing parameters.After aging at 800 ℃ for 30 min,outstanding strength(1500 MPa)and elongation(15％)were obtained.Considerable mechanical properties after aging stem from a triple strengthening mecha-nism,i.e.,L12 nanoprecipitates and rod-shaped B2 particles within the FCC matrix,along with Cr-enriched spherical nanoparticles in the B2 phase.Meanwhile,hierarchical structure,i.e.,FCC dominated matrix,a discontinuous B2 phase,a precipitation-free zone in the B2 phase,and a K-S orientation relationship be-tween FCC and B2,facilitate to maintain excellent plasticity.These results guide designing HEAs by AM with controllable microstructures and outstanding mechanical properties for industrial applications.
基金项目
Natural science foundation of China(52271046)
Natural science foundation of China(52171052)
Natural Science Foundation of Hunan Province,China(2022JJ20061)
Natural Science Foundation of Hunan Province,China(2023JJ30684)
Key R&D Program of Guangdong Province,China(2019B010943001)
Transformation and Industrialization Plan of Scientific and Technological Achievements of Hunan Province,China(2020GK2031)
National Natural Science Foundation of China(52171052)
funding from State Key Laboratory of Powder Metallurgy,Central South University and the Fundamental Research Funds for the C()
NETL
NSTL
万方数据