Recently, a research team led by Prof. Shen Baolong from the School of Materials Science and Engineering, SEU, in collaboration with the Jiangsu Provincial Key Laboratory for High Technology Research of Advanced Metallic Materials and the Key Laboratory of Aerospace Structures and Materials of the Ministry of Education, published a research paper entitled “Deformable Eutectic Alloy With Near‐Theoretical Yield Strength via Hierarchical Nanoscale Multiphases and Sessile Defects” in the international journal Advanced Science. This study successfully constructed hierarchical nanoscale multiphase structures and sessile defects in a CoCrFeNiTa0.4 eutectic high-entropy alloy, achieving a near-theoretical yield strength of 2.6 GPa along with 13.6% ductility. This work provides a novel approach to resolving the long-standing challenge of balancing strength and ductility in dual-phase and multiphase alloys caused by elasticmodulus and hardness mismatch.
Eutectic high-entropy alloys feature high strength, excellent microstructural stability, and corrosion resistance, holding promise for meeting stringent demands in lightweight design, long service life, and high reliability for applications such as aerospace high-temperature components, deep-sea pressure-resistant structures, and critical load-bearing parts in ships. However, traditional FCC/Laves-type eutectic high-entropy alloys often suffer from severe modulus/hardness mismatch between the two phases, weak interfacial bonding, and poor coordinated deformation capability, which can lead to early-stage fracture underloading, making it difficult to further enhance their yield strength—a core bottleneck limiting the development of this alloy system.
To address this challenge, the research team proposed a synergistic strategy involving copper-mold suction casting followed by aging treatment to regulate the CoCrFeNiTa0.4 eutectic high-entropy alloy. This process refines the lamellar structure to the nanoscale through large temperature gradients and high cooling rates. Subsequent structural regulation induces precipitation within both phases, forming a hierarchical nanoscale multiphase structure. The hard and brittle Laves phase transforms into a deformable D022 phase, forming a coherent interface with the FCC lamellae, while coherent L12 strengthening precipitates form within the soft and ductile FCC phase. These modifications can significantly reduce the modulus and hardness differences between the FCC and Laves phase layers, thereby successfully overcoming the long-standing strength-ductility trade-off. This breakthrough offers a viable solution for promoting the broader application of eutectic high-entropy alloys as advanced structural materials.
Luo Yusha, a PhD candidate from the School of Materials Science and Engineering, SEU, serves as the first author of the paper. Associate Prof. Wang Qianqian and Prof. Shen Baolong from SEU, along with Prof. Tong Yang from Yantai University, are the co-corresponding authors. SEU is the primary corresponding institution. This research was supported by the Key Program of the National Natural Science Foundation of China.
Paper's link: https://doi.org/10.1002/advs.202518764
Source: School of Materials Science and Engineering, SEU
Translated by: Melody Zhang
Proofread by: Gao Min
Edited by: Leah Li
