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<p>Titanium carbide (TiC) coatings are essential for carbon-based materials such as diamond by improving interfacial wettability and bonding with metallic components. However, the mechanical behavior of TiC coatings with typical epitaxial microstructures remains insufficiently understood. In this work, molecular dynamics simulations were employed to investigate the feature-size-dependent compressive deformation mechanisms of columnar-grained TiC coatings with varying in-plane grain sizes (<i>d</i>) and coating thicknesses (<i>h</i>). The results showed that both yield strength and flow stress exhibited a transition from strengthening to softening with increasing <i>d</i>, with a critical <i>d</i> of 5.1&#xa0;nm. Increasing <i>h</i> enhanced the compressive strength until reaching a saturation <i>h</i> of 15.6&#xa0;nm. Atomistic analyses revealed two distinct deformation mechanisms. Fine-grained coatings were dominated by grain-boundary-mediated deformation and structural instability, resulting in softening. For larger-grains (<i>d</i> &gt; 5.1&#xa0;nm), plastic deformation was governed by confined intragranular slip, accompanied by {111}-related dislocation activities and abundant stair-rod dislocations that contributed to strain hardening. However, further increasing <i>h</i> provided limited enhancement in dislocation storage, leading to a strength plateau. These findings provided atomistic insights into the relationship between microstructural characteristics and mechanical properties of TiC coatings.</p>

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Feature-size-dependent compressive deformation mechanisms of TiC coatings: an atomistic study

  • 期刊论文

  • 发表日期：

    2026年7月1日

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  • Jiahe Zhou,
  • Renzhi Luo,
  • Zhen Wu,
  • Huina Shan,
  • Xin He,
  • Chuanyang Lu,
  • Yafei Li,
  • Xingxing Wang,
  • Jianguo Yang,
  • Yanming He

摘要

Titanium carbide (TiC) coatings are essential for carbon-based materials such as diamond by improving interfacial wettability and bonding with metallic components. However, the mechanical behavior of TiC coatings with typical epitaxial microstructures remains insufficiently understood. In this work, molecular dynamics simulations were employed to investigate the feature-size-dependent compressive deformation mechanisms of columnar-grained TiC coatings with varying in-plane grain sizes (d) and coating thicknesses (h). The results showed that both yield strength and flow stress exhibited a transition from strengthening to softening with increasing d, with a critical d of 5.1 nm. Increasing h enhanced the compressive strength until reaching a saturation h of 15.6 nm. Atomistic analyses revealed two distinct deformation mechanisms. Fine-grained coatings were dominated by grain-boundary-mediated deformation and structural instability, resulting in softening. For larger-grains (d > 5.1 nm), plastic deformation was governed by confined intragranular slip, accompanied by {111}-related dislocation activities and abundant stair-rod dislocations that contributed to strain hardening. However, further increasing h provided limited enhancement in dislocation storage, leading to a strength plateau. These findings provided atomistic insights into the relationship between microstructural characteristics and mechanical properties of TiC coatings.