Atomic configurations of (001)_σ stacking disordering defects within σ phase in Ni-based single crystal superalloys

The σ topologically close-packed phase has long been regarded as detrimental to the mechanical performances of Ni-based single crystal superalloys. However, recent studies indicate that (001)_σ stacking disordering defects can mitigate the adverse effects. In this work, the atomic configurations of two distinct types of (001)_σ stacking disordering defects are systematically elucidated, and the resulting structural misalignments are quantitatively characterized. These findings reveal the intrinsic nature and geometric features of these defects, advancing the understanding of defect-mediated mechanisms in the σ phase. This work provides new insights into the defect engineering of the σ phase for the tailored design of next-generation Ni-based single crystal superalloys.