Tensile Properties and Serrated Flow Behavior of As-Cast CoCrFeMnNi High-Entropy Alloy at Room and Elevated Temperatures

The tensile properties and serrated flow behavior of as-cast CoCrFeMnNi high-entropy alloy were examined over a wide range of temperatures. Tensile elongations were higher at 22 °C than at high temperatures above 700 °C. With the increase in the temperature from 500 to 700 °C, distinct serration flows occurred and evolved in the sequence of type A, type B, and type C serrations. Anisotropy in the tensile properties and serrated flow was identified. The average stress drop amplitude in the serrated flow was generally higher when tensile loading was applied perpendicular to the columnar grain growth direction. Moreover, 700 °C, the strain increment required for subsequent stress drops was significantly lower when tensile loading was applied perpendicular to the columnar grain growth direction. The start and finish temperatures of serration flow were slightly higher in as-cast HEA by 100–200 °C compared to those in wrought HEA.