First-principles exploration of diffusion activation energy in CoCrNi and CoCrFeNiMn high-entropy alloys, with comparison to creep activation energy

High entropy alloys (HEAs) are potential candidates for high performance engineering material applications. Creep is permanent, time-dependent inelastic deformation under applied stress, and is often the failure mechanism for structural engineering alloys in service applications. Diffusion behavior is an important contribution to secondary creep behavior. In the present work, first-principles based calculations using density functional theory (DFT) are used to analyze activation energy for diffusion in the CoCrFeNiMn alloy and its constituent ternary systems. The relationship between creep activation energy and diffusion activation energy in well studied systems, such as CoCrNi, are explored. Special quasi-random structures (SQS) are employed, and complications related to structural complexity are discussed. Results are compared to known literature where available, and the importance of the calculations for novel alloy design are discussed.