期刊
ACTA MATERIALIA
卷 243, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2022.118516
关键词
High -entropy alloy; Heterogeneous structure; Strength and ductility; Hetero-deformation induced hardening; Strain hardening
In this study, a strategy of using a heterogeneous grain size structure and a reduced stacking fault energy was explored in a CoCrFeNiMn FCC high entropy alloy to overcome the strength-ductility trade-off. The alloy achieved high yield strength, tensile strength, and elongation to failure through cooperative strain hardening mechanisms. These micromechanisms of deformation helped refine the mean free paths for dislocations and improve the alloy's hardness.
Alloys with high yield strength and ductility are attractive for application because of their potential to offer mass reduction, energy savings, and enhanced structural reliability. However, increasing strength usually comes at the expense of ductility, which is commonly known as the strength-ductility trade-off for metal alloys. In this work, we explored a strategy of using a heterogeneous grain size structure and a reduced stacking fault energy in a CoCrFeNiMn FCC high entropy alloy to overcome the limitations of this trade-off. By this approach, the alloy achieved a yield strength of 980 MPa, a tensile strength of 1385 MPa, and tensile elongation to failure of 48% benefiting from cooperative strain hardening via multiple mech-anisms, such as hetero-deformation induced (HDI) hardening, deformation twinning, Frank-Read disloca-tion sources and Lomer-Cottrell dislocation locks instigated by such structures. These micromechanisms of deformation help to harden the alloy via in situ refinement of the mean free paths for dislocations.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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