文献类型：期刊文献

英文题名：Discontinuous precipitation enables an exceptional cryogenic strength-strain hardening synergy in a heterostructured medium entropy alloy

作者：Xie, Yu[1];Lu, Tiwen[1];Sun, Binhan[1];Yao, Ning[1];Chen, Xiyu[1];Yang, Xiaofeng[1];Wan, Bingbing[2];Zhang, Xian-Cheng[1];Tu, Shan-Tung[1]

机构：[1]East China Univ Sci & Technol, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China;[2]Dongguan Univ Technol, Sch Mat Sci & Engn, Dongguan 523808, Peoples R China

年份：2025

卷号：290

外文期刊名：ACTA MATERIALIA

收录：;EI(收录号：20251318111387);WOS:【SCI-EXPANDED(收录号:WOS:001456781200001)】；

基金：X.-C.Z. acknowledges the financial support from the National key research and development program (2022YFB4602100) and National Natural Science Foundation of China (No. 52205152, No. U21B2077) . T. L. is sponsored by Shanghai Pujiang Programme (No. 23FJD023) and Shanghai Explorer Program (No. 24TS1412000) . B.S. acknowledges the financial support from National Key R & D Program of China (No. 2023YFB3712100) and the National Natural Science Foundation of China (Grant No. 52275147) .

语种：英文

外文关键词：Medium-entropy alloys; Discontinuous precipitation; Cryogenic mechanical property; Strain hardening behavior; Heterostructure

摘要：Precipitation strengthening through coherent nanoprecipitates emerges as a desirable strategy to design highperformance materials for cryogenic applications. Generally, discontinuous precipitation (DP) is regarded as a detrimental factor to the strength and toughness of materials, and numerous methods are aimed at suppressing DP behavior. However, in this work, we utilized DP to develop a heterostructure in a fully recrystallized (CoCrNi)94Al3Ti3 medium-entropy alloy, resulting in an ultrahigh tensile strength of 1750 MPa and remarkable ductility of 34% at -173 degrees C. This exceptional mechanical property was attributed to the presence of fine and dense shearable nanoprecipitates and a high fraction of fine grains induced by optimized and pronounced DP behavior, respectively. In-situ high-temperature electron back-scatter diffraction (EBSD) and element distribution analysis revealed that the formation of heterogeneous grains was ascribed to the driving force provided by the chemical diffusion at DP reaction fronts across grain boundaries, leading to a diffusion-induced recrystallization. Further, the impressive strain-hardening rate at cryogenic temperature was attributed to three key factors: First, DP-induced heterogenous grains resulted in strong strain partitioning behavior, leading to a strong heterogeneous deformation induced (HDI) stress. Second, a strong dynamic slip refinement mechanism induced by shearable nanoprecipitate, contributed to the persistent generation of new slip bands and dislocation accumulation. Third, high flow stress, HDI effect and shearing mechanism jointly lead to unusual stacking faults and nanotwins, which impedes dislocation motion by reducing their mean free path. Overall, reasonable DP behavior provides a novel route for the design of precipitation-strengthening alloys for harsh environment applications.