Balancing κ-formation and γ-recrystallization towards exceptional mechanical properties in a NiCoV0.9 medium entropy alloy

作     者：Zhang, Yuxin He, Junyang Cai, Weijin Li, Na Chen, Zipan Xu, Xiangqi Chen, Yang Qi, Zhixiang Zheng, Gong Wei, Daixiu Tan, Xinrong Song, Min 

作者机构：State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China School of Mechanical Engineering Tongling University Tongling244061 China Key Laboratory of Construction Hydraulic Robots of Anhui Higher Education Institutes Tongling University Tongling244061 China Jiangsu Belight Laboratory State Key Laboratory of Advanced Casting Technologies University of Science and Technology Nanjing210094 China Hunan University of Science and Technology Xiangtan411201 China 

出 版 物：《Intermetallics》 (Intermet)

年 卷 期：2025年第179卷

核心收录：

学科分类：080701[工学-工程热物理] 0806[工学-冶金工程] 08[工学] 0807[工学-动力工程及工程热物理] 

基　　金：This work was financially supported by National Key Research and Development Program of China (No. 2022YFE0134400)  National Natural Science Foundation of China (Grant No. 52101207  52205150)  Natural Science Foundation of Hunan Province (Grant No. 2023JJ40725) and Key Laboratory of Construction Hydraulic Robots of Anhui Higher Education Institutes  Tongling University (Grant No. TLXYCHR-O-21ZD02). MS acknowledges the financial support from the Science and Technology Innovation Program of Hunan Province (No. 2022RC3035) 

主　　题：Annealing 

摘      要：In this work, by lowering the V amount, two thermodynamic processes, i.e., κ-formation and γ-recrystallization, are near-concurrently activated in a NiCoV0.9 medium entropy alloy (MEA) during 900 °C annealing. The NiCoV0.9 MEA with only 2 min annealing inherits the high strength from the cold-rolling structure while regains apparent work-hardening, endowing the alloy at this state with excellent strength-ductility synergy. By utilizing correlated observation methods, it is found that in the very beginning of annealing, γ-recrystallization occurs closely prior to κ transformation, which in turn enables elemental redistribution needed for κ growth. Further in-situ synchrotron high-energy X-ray diffraction reveals the synchronous onset of plastic deformation in both κ and γ, suggesting the good deformability of κ regardless of its hard nature. With prolonged annealing at 900 °C, the yield strength drops sharply yet the ductility is not further enhanced. This is likely due to the fast increment in both size and volume fraction of the κ phase that significantly raises the cracking sensitivity. © 2025 Elsevier Ltd