Anomalous size effect in micron-scale CoCrNi medium-entropy alloy wire

SCRIPTA MATERIALIA

卷:199

Article

Chen, Jin-Xi^1,2  Chen, Yan^1,2  Liu, Jun-Peng¹  Liu, Tian-Wei^1,2  Dai, Lan-Hong^1,2,3 

[1] Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China

[2] Univ Chinese Acad Sci, Sch Engn Sci, Beijing 101408, Peoples R China

[3] Beijing Inst Technol, State Key Lab Explos Sci & Technol, Beijing 100081, Peoples R China

关键词: Medium-entropy alloy wire;    Size effect;    Strain gradient;    Multiple deformation twins;   

DOI  :  10.1016/j.scriptamat.2021.113897

来源: Elsevier

【 摘 要 】

Micron-sized CoCrNi medium-entropy alloy (MEA) wires are successfully fabricated by Taylor-Ulitovsky method for the first time. The wires of two different sizes, with diameters of 40 and 100 microns, ex-hibit an excellent combination of tensile strength and ductility. In-depth microstructure characterization indicates the superior mechanical properties stem from the synergy of Lomer-Cottrell locks, mechani-cal nano-twinning and HCP stacking. Surprisingly, an anomalous size effect is presented in the tension of these microwires, i.e., the much higher tension strength and ductility are observed in the 40 micron-wire, in sharp contrast to conventional single-principal element alloys only showing negligibly minor tension size effect. Much higher density of geometrically necessary dislocation accompanying heterogeneous de-formation is observed in 40 micron-wire, leading to a high strain gradient, which is in turn joined with multiple deformation twins giving rise to high strength and ductility in 40 micron-wire. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

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