Mechanical properties and deformation twinning behavior of as-cast CoCrFeMnNi high-entropy alloy at low and high temperatures

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 712; pp. 108 - 113
• Main Authors: Kim, Jeoung Han, Lim, Ka Ram, Won, Jong Woo, Na, Young Sang, Kim, Hyoung-Seop
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 17.01.2018; Elsevier BV
• Subjects: Casting structure; Crystallography; Deformation; Deformation twinning; Ductility; Electron microscopy; Entropy; High entropy alloys; Impact strength; Mechanical properties; Strain hardening; Strain localization; Tensile properties; Twinning; High entropy alloys; Mechanical properties; Deformation twinning; Casting structure; Strain hardening
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2017.11.081

Tensile properties of an as-cast CoCrFeMnNi high-entropy alloy were investigated at various temperatures ranging from −160 to 1000°C. The tensile strength and ductility did not vary significantly with loading direction, despite the alloy’s strongly preferred crystallographic orientation. The impact toughness values of the as-cast high-entropy alloy were much higher than those of many traditional alloys, particularly at low temperatures. The mechanical properties of the as-cast high-entropy alloy were compared with those of wrought high-entropy alloy and noticeable differences between the two alloys were found. The maximum tensile ductility and three different strain hardening stages were observed at 500°C in the as-cast structure. Transmission electron microscopy observations demonstrated that the initiation of deformation twinning was very active even at 500°C. A simple calculation suggests that very large grains of the as-cast structure induced a reduction in twinning stress, retarding the onset of strain localization.