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<p>This study systematically investigates the atomistic-scale anisotropic deformation mechanisms and microstructural evolution of single-crystal Nb shocked along the [100], [110], and [111] orientations using molecular dynamics (MD) simulations. The results show that all orientations exhibit elastoplastic two-wave characteristics, with the [110] orientation yielding first due to its lowest critical resolved shear stress. The [100] orientation develops a stable anti-twinning network with multiple slip systems, where plastic deformation is co-dominated by anti-twinning and dislocations. In contrast, [110] and [111] orientations undergo twinning nucleation at the plastic front alongside dense dislocation networks. Subsequent stress relaxation and temperature rise induce detwinning, shifting the deformation mechanism from twin–dislocation co-dominance to dislocation-dominated plasticity. Moreover, anti-twin and twin boundaries migrate via rapid dislocation reactions at boundary steps, driving anti-twin thickening, twin growth, and detwinning. This work establishes crystal orientation as a key factor governing plastic behavior and provides theoretical guidance for designing impact-resistant materials.</p>

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Anisotropic Twinning and Anti-twinning Dominated Plasticity in Nb Single Crystals under High-Strain-Rate Shock Loading

  • 期刊论文

  • 发表日期：

    2026年4月29日

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  • Xiaotian Yao,
  • Sen Chen,
  • Chengda Dai,
  • Jianbo Hu

摘要

This study systematically investigates the atomistic-scale anisotropic deformation mechanisms and microstructural evolution of single-crystal Nb shocked along the [100], [110], and [111] orientations using molecular dynamics (MD) simulations. The results show that all orientations exhibit elastoplastic two-wave characteristics, with the [110] orientation yielding first due to its lowest critical resolved shear stress. The [100] orientation develops a stable anti-twinning network with multiple slip systems, where plastic deformation is co-dominated by anti-twinning and dislocations. In contrast, [110] and [111] orientations undergo twinning nucleation at the plastic front alongside dense dislocation networks. Subsequent stress relaxation and temperature rise induce detwinning, shifting the deformation mechanism from twin–dislocation co-dominance to dislocation-dominated plasticity. Moreover, anti-twin and twin boundaries migrate via rapid dislocation reactions at boundary steps, driving anti-twin thickening, twin growth, and detwinning. This work establishes crystal orientation as a key factor governing plastic behavior and provides theoretical guidance for designing impact-resistant materials.