Interaction mechanism of dislocations with Bi/hBN nanoparticles in free- cutting steels: molecular dynamics simulations

GY Li and FZ Wang and ZW Chen and Y Fan and P Li and MH Liu and K Jiang, PHYSICA SCRIPTA, 100, 025922 (2025).

DOI: 10.1088/1402-4896/ada4f6

To further understand the mechanical properties of free-cutting steels, we employed molecular dynamics (MD) simulations to investigate the interaction mechanisms between dislocation slip along close-packed planes and nano-inclusion particles (Bi/h-BN) within single-crystal iron (Fe). By colliding dislocations at varying slip velocities with nanometer-scale particles of different sizes and compositions, we concluded that particle diameter plays a decisive role not only in determining the dislocation cutting mode but also in influencing the dislocation's shear stress response. These indicate that: Larger particles significantly enhance the strengthening effect on the matrix. Additionally, higher dislocation slip velocities result in stronger particle interaction feedback and greater particle damage, contributing to increased matrix deformation. h-BN particles, owing to their much higher hardness compared to Bi, exhibited superior resistance to deformation, requiring higher dislocation shear stress to pass these obstacles.

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