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<p>Atomistic simulations were conducted to clarify shock-driven microstructural evolution and plasticity in a polycrystalline eutectic AlCoFeCrNi<sub>2.1</sub> high-entropy alloy at room temperature over particle velocities <i>Up</i> = 0.2–0.5&#xa0;km/s. At <i>Up</i> = 0.2&#xa0;km/s, the response is dominated by elastic accommodation with minor grain-boundary sliding, and defects remain largely confined to grain-boundary networks. As <i>Up</i> increases, the alloy transitions to a shear-localised plastic regime marked by a progressive FCC-to-HCP-like structural change with a minor BCC-like fraction. Extensive intrinsic stacking-fault bands propagate into grains along {111} planes, inclined at ∼&#xa0;45 to the loading direction; at <i>Up</i> = 0.5&#xa0;km/s, these bands thicken through the formation of extrinsic faults and deformation twins and are accompanied by locally disordered regions. Dislocation analysis identifies Shockley partials as the primary carriers of plasticity, with a monotonic increase in density with <i>Up</i>. Grain boundaries act as dominant sources and sinks for dislocations and planar faults, promoting emission, absorption and pile-up. Reactions among partials generate perfect dislocations and sessile junctions (e.g., Lomer–Cottrell-type locks), which pin fault ribbons and contribute to strain hardening. The spatial co-localisation of fault/twin bands with high-shear regions indicates that the shock response is governed by the coupled interplay of partial-dislocation glide, planar-fault/twinning evolution and shear localisation.</p>

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Molecular dynamics study of the microscopic deformation mechanisms of AlCoFeCrNi2.1 high-entropy alloy under different shock velocities

  • 期刊论文

  • 发表日期：

    2026年6月17日

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  • Xixiang Mao,
  • Xinyi Yang,
  • Bensheng Huang,
  • Junlin Wang,
  • Maoming Chen,
  • Chengyu Shen

摘要

Atomistic simulations were conducted to clarify shock-driven microstructural evolution and plasticity in a polycrystalline eutectic AlCoFeCrNi2.1 high-entropy alloy at room temperature over particle velocities Up = 0.2–0.5 km/s. At Up = 0.2 km/s, the response is dominated by elastic accommodation with minor grain-boundary sliding, and defects remain largely confined to grain-boundary networks. As Up increases, the alloy transitions to a shear-localised plastic regime marked by a progressive FCC-to-HCP-like structural change with a minor BCC-like fraction. Extensive intrinsic stacking-fault bands propagate into grains along {111} planes, inclined at ∼ 45 to the loading direction; at Up = 0.5 km/s, these bands thicken through the formation of extrinsic faults and deformation twins and are accompanied by locally disordered regions. Dislocation analysis identifies Shockley partials as the primary carriers of plasticity, with a monotonic increase in density with Up. Grain boundaries act as dominant sources and sinks for dislocations and planar faults, promoting emission, absorption and pile-up. Reactions among partials generate perfect dislocations and sessile junctions (e.g., Lomer–Cottrell-type locks), which pin fault ribbons and contribute to strain hardening. The spatial co-localisation of fault/twin bands with high-shear regions indicates that the shock response is governed by the coupled interplay of partial-dislocation glide, planar-fault/twinning evolution and shear localisation.