期刊
出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2023.145597
关键词
High-entropy alloys; Gradient hierarchical nanostructure; Precipitates; Hetero-deformation-induced hardening; Strength-ductility synergy
Gradient microstructural design is a new strategy for enhancing the strength-ductility synergy of high/medium entropy alloys. This study reports a three-level gradient hierarchical nanostructure in Al0.3CoCrFeNi HEA achieved through ultrasonic surface rolling processing and aging treatment, which significantly increases yield strength without sacrificing ductility.
Gradient microstructural design represents a new strategy for enhancing strength-ductility synergy of high/ medium entropy alloys (H/MEAs). However, most of the reported gradient H/MEAs have only one type of gradient microstructure, which has limited ability to realize the full potential of gradient structure. Here, we report a three-level gradient hierarchical nanostructure (GHN) in a Al0.3CoCrFeNi HEA by ultrasonic surface rolling processing (USRP) followed by aging treatment that can result in a six-fold enhancement in yield strength with almost no loss in ductility compared to the coarse structured counterpart. The proposed three-level GHN is characterized with gradient variations in grain size, nano-twin and dislocation density, B2 and & sigma; precipitates content. Systematic experiments indicate that strong hetero-deformation-induced (HDI) hardening associated with the activation of deformation twinning, are responsible for this exceptional strength-ductility synergy. This three-level GHN engineering strategy in this work can also be feasibly applied to many other H/MEAs, and offers an available pathway to develop high strong and ductile metallic materials.
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