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<p>The formation mechanism of twinning structures in the Ti<sub>2</sub>N nitride layer of plasma-nitrided TC6 titanium alloy remains unclear. This study uses molecular dynamics (MD) simulations combined with an orthogonal experimental design to systematically investigate the effects of Al, Cr, and Mo on twin formation in the Ti<sub>2</sub>N layer. The results show that Cr and Mo promote the growth of twinning structures due to their negative stacking fault energies (<i>γ</i><sub>ISF</sub> = -141.565 mJ/m<sup>2</sup> and − 75.172mJ/m<sup>2</sup>, respectively), while Al has the opposite effect. The optimal condition for twin formation is identified as Cr doping along the [100] direction at a strain rate of 0.3%/ps and a temperature of 1073&#xa0;K. Microstructural analysis indicates that the annihilation of positive and negative dislocations leads to the formation of three-dimensional dislocation networks. These networks pin lattice distortions and facilitate crystallographic reorientation between neighboring grains, ultimately initiating twin boundaries. This work provides insight into how alloying elements synergistically influence stacking fault energy and lattice distortion, offering a theoretical basis for designing high-strength titanium alloy surface treatments.</p>

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Ti2N twin formation ability affected by alloying element in the TC6 titanium alloy: MD simulation

  • 期刊论文

  • 发表日期：

    2025年9月16日

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  • Yaoge Du,
  • Guifa Li,
  • Qing Deng,
  • Yongxiang Geng,
  • Yixin Xiao,
  • Haizhong Zheng,
  • Ping Peng

摘要

The formation mechanism of twinning structures in the Ti2N nitride layer of plasma-nitrided TC6 titanium alloy remains unclear. This study uses molecular dynamics (MD) simulations combined with an orthogonal experimental design to systematically investigate the effects of Al, Cr, and Mo on twin formation in the Ti2N layer. The results show that Cr and Mo promote the growth of twinning structures due to their negative stacking fault energies (γISF = -141.565 mJ/m2 and − 75.172mJ/m2, respectively), while Al has the opposite effect. The optimal condition for twin formation is identified as Cr doping along the [100] direction at a strain rate of 0.3%/ps and a temperature of 1073 K. Microstructural analysis indicates that the annihilation of positive and negative dislocations leads to the formation of three-dimensional dislocation networks. These networks pin lattice distortions and facilitate crystallographic reorientation between neighboring grains, ultimately initiating twin boundaries. This work provides insight into how alloying elements synergistically influence stacking fault energy and lattice distortion, offering a theoretical basis for designing high-strength titanium alloy surface treatments.