Plastic deformation of single crystals of the equiatomic Cr−Mn−Fe−Co−Ni high-entropy alloy in tension and compression from 10 K to 1273 K

The plastic deformation behavior of single crystals of the quinary, equiatomic Cr−Mn−Fe−Co−Ni high-entropy alloy (HEA) with the face-centered cubic structure has been investigated in tension and compression as a function of crystal orientation and temperature from 10 K to 1373 K. The critical resolv...

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Veröffentlicht in:Acta materialia 2021-01, Vol.203 (C), p.116454, Article 116454
Hauptverfasser: Kawamura, Marino, Asakura, Makoto, Okamoto, Norihiko L., Kishida, Kyosuke, Inui, Haruyuki, George, Easo P.
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Sprache:eng
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Zusammenfassung:The plastic deformation behavior of single crystals of the quinary, equiatomic Cr−Mn−Fe−Co−Ni high-entropy alloy (HEA) with the face-centered cubic structure has been investigated in tension and compression as a function of crystal orientation and temperature from 10 K to 1373 K. The critical resolved shear stress (CRSS) for {111} slip at room temperature is 42−45 MPa. It does not depend much on crystal orientation (i.e., the Schmid law holds true) and the sense (tension vs. compression) of the applied load. The CRSS for {111} slip increases with the decrease in temperature, without showing any significant inertia effects at cryogenic temperatures below 77 K. Extrapolation from the measured yield stresses down to 10 K yields a CRSS value at 0 K of 168 MPa. At cryogenic temperatures, the measured strain-rate sensitivity of flow stress is consistent with a very small activation volume. The concept of stress equivalence holds true both for the temperature dependence of CRSS and the stress dependence of activation volume, indicating that solid-solution hardening is the major strengthening mechanism. Deformation twinning occurs at 77 K but not at room temperature, resulting in higher tensile elongation to failure at 77 K than at room temperature. Deformation twinning at 77 K occurs at a shear stress of 378 MPa on conjugate (1¯1¯1) planes in the form of Lüders deformation after large plastic strain (about 85%) achieved by the stage I (easy glide) and stage II (linear work-hardening) deformation. [Display omitted]
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2020.10.073