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

Abstract

Tensile properties of an as-cast CoCrFeMnNi high-entropy alloy were investigated at various temperatures ranging from -160 to 1000 degrees 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 degrees C in the as-cast structure. Transmission electron microscopy observations demonstrated that the initiation of deformation twinning was very active even at 500 degrees 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.