文献类型：期刊文献

英文题名：Ultrastrong and ductile additively manufactured precipitation-hardening medium-entropy alloy at ambient and cryogenic temperatures

作者：Yao, Ning[1];Lu, Tiwen[1,4];Feng, Kai[2];Sun, Binhan[1];Wang, Run-Zi[3];Wang, Ji[1];Xie, Yu[1];Zhao, Pengcheng[1];Han, Bolun[2];Zhang, Xian-Cheng[1];Tu, Shan -Tung[1]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China;[2]Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Mat Laser Proc & Modificat, Shanghai 200240, Peoples R China;[3]Tohoku Univ, Fracture & Reliabil Res Inst, Grad Sch Engn, Sendai, Miyagi 9808579, Japan;[4]East China Univ Sci & Technol, Shanghai, Peoples R China

年份：2022

卷号：236

外文期刊名：ACTA MATERIALIA

收录：;EI(收录号：20222812352129);WOS:【SCI-EXPANDED(收录号:WOS:000831014700002)】；

基金：Acknowledgement This work was financially supported by the National Nat-ural Science Foundation of China (Nos. 51725503, 52005185, 52011530036, U21B2077, 52105144) , the Young Elite Scientists Sponsorship Program by CAST (YESS20200029) . Tiwen Lu thanks Shanghai Super Postdoctoral Incentive Plan (No. 2021103) .

语种：英文

外文关键词：Medium-entropy alloys; Additive manufacturing; Precipitation hardening; Hierarchical microstructure; Cryogenic temperature

摘要：Strong and ductile precipitation-hardening face-centered cubic medium-entropy alloys (MEAs) are potential structural material candidates for cryogenic applications, which, however, are rarely reported in the field of additive manufacturing. In this work, we develop a high-performance (CoCrNi)(94)Al3Ti3 MEA via additive manufacturing and age hardening. Superior tensile strength-ductility combinations, in comparison to other reported additively manufactured face-centered cubic metals, are achieved at both ambient (293 K) and cryogenic (103 K) temperatures. This is attributed to the hierarchical microstructure with a high degree of heterogeneity in terms of grain size, cellular substructure and characteristics of nanoprecipitates (L1(2) phase). Such microstructure feature leads to a higher ambient-temperature yield strength (921.1 MPa) and ultimate tensile strength (1346.4 MPa) than the as-printed sample that possesses a homogeneous microstructure. Moreover, the precipitate shearing mechanism, hetero-deformation induced hardening effect and deformation-induced stacking faults-based substructure evolution jointly result in a high and persistent strain hardening ability, which ensures a high ductility (27.2% at ambient temperature). The testing at the cryogenic temperature promotes the efficiency of hetero-deformation induced hardening and the formation of stacking faults, leading to an excellent strength-ductility combination (tensile strength 1702.9 MPa and ductility 25.4%). However, unlike the simultaneous increment of strength and ductility for the as-printed sample when the testing temperature decreases from 293 K to 103 K, the ductility of the age-hardened sample at different temperatures only changes slightly. This feature is related to the severe strain/stress concentrations developed within the heterogeneous microstructure of the age-hardened sample at 103 K. Our approach of introducing coherent nanoprecipitates in the additively manufactured microstructure provides a new insight into the development of high-performance MEAs for cryogenic applications. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.