Analysis of the temperature-dependent plastic deformation of single crystals of quinary, quaternary and ternary equiatomic high- and medium-entropy alloys of the Cr-Mn-Fe-Co-Ni system

• Published in: Science and technology of advanced materials Vol. 25; no. 1; p. 2376524
• Main Authors: Li, Le, Chen, Zhenghao, Tei, Seiko, Matsuo, Yusuke, Chiba, Ryosuke, Yuge, Koretaka, Inui, Haruyuki, George, Easo P.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis Ltd 01.12.2024; Taylor & Francis; Taylor & Francis Group
• Subjects: Chromium; Cobalt; critical resolved shear stress; Crystal dislocations; Deformation analysis; Dislocation mobility; Drag coefficients; Engineering and Structural materials; Entropy; Entropy of activation; Face centered cubic lattice; High entropy alloys; Iron; Manganese; mean-square atomic displacement; Medium entropy alloys; Nickel; Phonon drag; Plastic deformation; Room temperature; Shear stress; Single crystals; Solid solutions; Solution strengthening; Temperature; Temperature dependence; thermal activation; critical resolved shear stress; High-entropy alloys; thermal activation; single crystals; mean-square atomic displacement
• ISSN: 1468-6996; 1878-5514
• DOI: 10.1080/14686996.2024.2376524

Temperature-dependent plastic deformation behaviors of single crystals of quaternary and ternary equiatomic medium-entropy alloys (MEAs) belonging to the Cr-Mn-Fe-Co-Ni system were investigated in compression at temperatures in the range 9 K to 1373 K. Their critical resolved shear stresses (CRSSs) increase with decreasing temperature below room temperature. There is also a dulling of the temperature dependence of CRSS below 77 K due to dislocation inertial effects that we attribute to a decrease in the phonon drag coefficient. These behaviors were compared with those of previously investigated single crystals of the equiatomic Cr-Co-Ni and Cr-Fe-Co-Ni MEAs, and the equiatomic Cr-Mn-Fe-Co-Ni high-entropy alloy (HEA). The temperature dependence of CRSS and the apparent activation volumes below room temperature can be well described by conventional thermal activation theories of face-centered cubic (FCC) alloys. Above 673 K, there is a small increase in CRSS, which we believe is due to elastic interactions between solutes and mobile dislocations, the so-called Portevin-Le Chatelier (PL) effect. The CRSS at 0 K was obtained by extrapolation of fitted CRSS vs. temperature curves and compared with predictions from solid solution strengthening models of HEA and MEAs.