TY - JOUR
T1 - Calculation-driven design of off-equiatomic high-entropy alloys with enhanced solid-solution strengthening
AU - Li, Jiaxiang
AU - Yamanaka, Kenta
AU - Chiba, Akihiko
N1 - Funding Information:
This work was supported by the Grant-in-Aid for Scientific Research on Innovative Area “High Entropy Alloys” [grant number 18H05455 ] and the Grant-in-Aid for Young Scientists (A) [grant number 17H04957 ] through the Japan Society for the Promotion of Science (JSPS). The author, J. Li, holds a scholarship provided by China Scholarship Council.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/6/10
Y1 - 2021/6/10
N2 - Addition of Mo to the face-centered cubic (fcc) NiCoCrFe base alloy is an attractive method for improving the solid-solution strengthening of high-entropy alloys (HEAs). However, the low solubility of Mo in the equiatomic base alloy limits implementation. In this study, we used thermodynamic and ab initio calculations to develop an off-equiatomic NiCoCrFe-based HEA with an Mo content of up to 11.11 at%. Thermodynamic phase diagrams were constructed for the derived quinary subsystems with various Mo contents, and potential precipitate-free HEA compositions were determined. The degrees of lattice distortion (DLD) in seven selected HEAs were evaluated by statistically analyzing bond lengths determined using ab initio calculations. This approach could accurately predict the relative magnitudes of DLDs for multiple off-equiatomic HEAs in the studied system. Consequently, an off-equiatomic Ni1.8Co0.95Cr0.8Fe0.25Mo0.475 HEA was designed with enhanced lattice distortion, solid-solution strengthening, and yield strength. Microscopic analysis confirmed that the designed HEA exhibited a single fcc lattice, while excess Mo was detected at the grain boundary (GB) in a coarse-grained sample. It was deduced that slight GB segregation had a negligible influence on the lattice concentrations and solid-solution strengthening.
AB - Addition of Mo to the face-centered cubic (fcc) NiCoCrFe base alloy is an attractive method for improving the solid-solution strengthening of high-entropy alloys (HEAs). However, the low solubility of Mo in the equiatomic base alloy limits implementation. In this study, we used thermodynamic and ab initio calculations to develop an off-equiatomic NiCoCrFe-based HEA with an Mo content of up to 11.11 at%. Thermodynamic phase diagrams were constructed for the derived quinary subsystems with various Mo contents, and potential precipitate-free HEA compositions were determined. The degrees of lattice distortion (DLD) in seven selected HEAs were evaluated by statistically analyzing bond lengths determined using ab initio calculations. This approach could accurately predict the relative magnitudes of DLDs for multiple off-equiatomic HEAs in the studied system. Consequently, an off-equiatomic Ni1.8Co0.95Cr0.8Fe0.25Mo0.475 HEA was designed with enhanced lattice distortion, solid-solution strengthening, and yield strength. Microscopic analysis confirmed that the designed HEA exhibited a single fcc lattice, while excess Mo was detected at the grain boundary (GB) in a coarse-grained sample. It was deduced that slight GB segregation had a negligible influence on the lattice concentrations and solid-solution strengthening.
KW - Ab initio calculation
KW - High-entropy alloy
KW - Lattice distortion
KW - Solid-solution strengthening
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U2 - 10.1016/j.msea.2021.141359
DO - 10.1016/j.msea.2021.141359
M3 - Article
AN - SCOPUS:85105597561
SN - 0921-5093
VL - 817
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
M1 - 141359
ER -