In Situ Explorations of Serrated Plastic Flow in a CoCrFeNiW-C Alloy at Elevated Temperatures

Multi-component Co-alloys are a class of promising metallic materials for high-temperature applications. Provided the appreciable screening of their yield strength preservation trends depending on different alloy design strategies, systematic understandings of their plastic deformation response are still in lack. The present work is focused on the plastic deformation mechanisms of a CoCrFeNiW-C alloy in the 650-750 ^oC temperature range, with emphases on dislocation slip intermittency and the resultant serrated plastic flow. By integrating high-temperature <i>in situ</i> SEM-based tests, statistical analyses, and theoretical calculations, the following mechanistic insights will be discussed: (1) What causes the serrated plastic flow response and thereby the transition in its module? (2) What are the latent dynamic features amongst the serration incidents? (3) What kinds of deformation substructures are associated with the serrated plastic flow? Quantitative analysis of the dislocation slip mechanisms as well as their impacts on damage initiation will also be revealed in greater depth.