Nanostructure Evolution and Rupture Mechanisms in Layered Fe-Cr-Ni Alloy under Multiaxial Tensile Deformation: A Molecular Dynamics Study

This study investigates the rupture mechanism of layered Fe-Cr-Ni alloy under multiaxial tensile deformation using molecular dynamics simulations. The results found that the presence of layered orientation of Fe-Cr-Ni significantly impacts nanovoid formation, growth, and coalescence during multiaxial (uniaxial, biaxial, and triaxial) deformation. During triaxial deformation, nanovoids nucleate early and grow rapidly, leading to material failure, with body-centered cubic structure forming around void surfaces due to strain-induced phase transformations. Biaxial tensile deformation facilitates minor amount of face-centered cubic to body-centered cubic transformations with rectangular and square-shaped stacking faults. Uniaxial tensile deformation produces the highest degree of dislocation interactions, leading to complex defect structures. Our study highlights that the yield stress, dislocation density, surface area, and solid volume vary across different deformation modes. Layered or twin boundaries act as barriers for movement of dislocation, reducing the plasticity and enhancing void nucleation. Our findings provide critical insights into atomic-scale mechanisms driving void formation, phase transformation, and material failure in Fe-Cr-Ni alloys with twin boundaries, contributing to improved material design under multiaxial loading conditions.