Deformation mechanism differences of lamellar/core-shell FCC/B2 composites: atomic simulation study
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Abstract
AlCoCrFeNi eutectic multi-principal element alloys exhibit remarkable application potential owing to their inherent heterostructures and outstanding mechanical properties. Their mechanical behaviors are governed by the synergistic deformation of non-uniformly distributed face-centered cubic (FCC) and B2 phases. Clarifying the synergistic deformation mechanisms of FCC/B2 composites is therefore essential. Herein, molecular dynamics simulations are employed to investigate the mechanical behaviors and deformation mechanisms of FCC/B2 composites with lamellar and core-shell structures in AlCoCrFeNi2.1, Fe20Co20Ni41Al19 (at.%), and Ni + NiAl alloys. The results demonstrate that the elastic modulus of all composites is nearly identical during the elastic deformation stage. Upon yielding, lamellar samples display a higher yield stress yet poorer plasticity compared with the core-shell samples. The B2-core structure exhibits excellent plastic deformation capability, which originates from the coordinated activation of abundant dislocations, twins, and stacking faults suppressing void expansion. For lamellar samples, decreasing elemental diversity enhances yield strength by stabilizing heterogeneous interfaces and elevating the stacking fault energy of the FCC phase. Nevertheless, the scarcity of deformation systems promotes defect accumulation and accelerated void growth along phase boundaries, thereby degrading the material ductility. Differently, the yield strength of the core-shell composite is less sensitive to element composition. Compared with multi-principal element alloys, pure Ni in the Ni + NiAl model exhibits higher stacking fault energy and milder lattice distortion, which hinders the activation of Shockley partial dislocations and reduces dislocation storage capacity, thereby leading to inferior plasticity. The present findings provide theoretical guidance for developing high-strength-ductility alloys with non-uniform structures.
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Zhang, H.; Jia, N.; Wang, M.; Zheng, A.; Ji, H. Deformation mechanism differences of lamellar/core-shell FCC/B2 composites: atomic simulation study. Microstructures 2026, 6, 20260133. https://dx.doi.org/10.20517/microstructures.2026.156
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