TY - JOUR
T1 - Significant lattice-distortion effect on compressive deformation in Mo-added CoCrFeNi-based high-entropy alloys
AU - Li, Jiaxiang
AU - Yamanaka, Kenta
AU - Chiba, Akihiko
N1 - Funding Information:
This research was supported by a Grant-in-Aid for Scientific Research on Innovative Area “High Entropy Alloys” (No. 18H05455 ) and a Grant-in-Aid for Young Scientists (A) (No. 17H04957 ) awarded by the Japan Society for the Promotion of Science (JSPS) .
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/1/7
Y1 - 2022/1/7
N2 - Large lattice distortion is an essential feature of high-entropy alloys (HEAs). Herein, the deformation behaviors of three types of as-cast CoCrFeNi-based HEAs, which contained 0, 7.9, and 17.1 wt% Mo, were comparatively studied through compressive tests and microstructural observations. The intrinsic lattice distortion increased mainly as a function of the Mo content. By virtue of both the local strain incompatibility inside the coarse columnar grains of the as-cast microstructures and low dislocation mobility in HEAs, domain rotations were induced at low strains. Meanwhile, simple shear occurred between domains and produced a new boundary network in the microstructure. The large lattice distortion of the high-Mo HEA (17.1 wt%) gave rise to intense planar slip bands, on which a large number of dislocations slipped and impinged on strain-induced boundaries. As a result of the high back-stress hardening, the high-Mo HEA exhibited enhanced strain-hardening. At high strains, the stress concentration events increased as the lattice distortion of the HEAs increased; this promoted twin growth in the high-Mo HEA. The high-Mo HEA was highlighted with a high strain-hardening rate over a wide strain range. In this study, high-strength as-cast HEAs were developed based on the utilization of the lattice-distortion effect.
AB - Large lattice distortion is an essential feature of high-entropy alloys (HEAs). Herein, the deformation behaviors of three types of as-cast CoCrFeNi-based HEAs, which contained 0, 7.9, and 17.1 wt% Mo, were comparatively studied through compressive tests and microstructural observations. The intrinsic lattice distortion increased mainly as a function of the Mo content. By virtue of both the local strain incompatibility inside the coarse columnar grains of the as-cast microstructures and low dislocation mobility in HEAs, domain rotations were induced at low strains. Meanwhile, simple shear occurred between domains and produced a new boundary network in the microstructure. The large lattice distortion of the high-Mo HEA (17.1 wt%) gave rise to intense planar slip bands, on which a large number of dislocations slipped and impinged on strain-induced boundaries. As a result of the high back-stress hardening, the high-Mo HEA exhibited enhanced strain-hardening. At high strains, the stress concentration events increased as the lattice distortion of the HEAs increased; this promoted twin growth in the high-Mo HEA. The high-Mo HEA was highlighted with a high strain-hardening rate over a wide strain range. In this study, high-strength as-cast HEAs were developed based on the utilization of the lattice-distortion effect.
KW - Back-stress hardening
KW - Deformation twinning
KW - Domain rotation
KW - High-entropy alloy
KW - Lattice-distortion effect
KW - Simple shear
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U2 - 10.1016/j.msea.2021.142295
DO - 10.1016/j.msea.2021.142295
M3 - Article
AN - SCOPUS:85119047972
SN - 0921-5093
VL - 830
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
M1 - 142295
ER -