Defect Healing Mechanism in Fe-Cr-Ni Single Crystal Alloy Under Multiaxial Cyclic Loading: A Molecular Dynamics Simulation-Based Study

Abstract

This study uses molecular dynamics (MD) simulations to investigate the defect healing mechanisms in Fe-Cr-Ni single crystal alloys under multiaxial cyclic loading. Focusing on enhancing the mechanical strength of these alloys for aerospace, automotive, nuclear, and marine applications, the research examines atomic-scale healing of preexisting defects. Triaxial cyclic loading simulations at 300 K reveal that defect healing primarily occurs through dislocation cross-slip, climb, atomic diffusion, and crystalline structure recovery. The closure of voids is facilitated by dislocation tangle formation, stacking fault evolution, and extrinsic-to-intrinsic stacking fault transitions. Complete void healing is achieved by the 15th cycle in triaxial loading, 19th in biaxial, and 27th in uniaxial loading. Phase transformation analysis confirms the dominance of the FCC phase, with localized HCP formations aiding structural recovery. These findings provide critical insights into the atomic-scale defect healing mechanism, offering strategies to enhance fatigue resistance, structural integrity, and long-term performance of Fe-Cr-Ni alloys under cyclic loading.