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<p>TiAl alloys, as a new generation of lightweight high-temperature materials, exhibit significant application potential in aerospace engines and related advanced propulsion systems. Gradient structures represent an effective strategy for manufacturing metals with superior mechanical properties. However, the deformation mechanisms of gradient nanograined (GNG) γ-TiAl alloys remain incompletely understood. In this work, we investigated the effects of different grain sizes and gradient structures on the uniaxial tensile deformation behavior of γ-TiAl alloys using molecular dynamics simulation methods. The results indicate that the peak strength occurs at a critical grain size of 21&#xa0;nm. Below 21&#xa0;nm, grain boundary migration and grain rotation dominate as the primary deformation mechanisms governing the inverse Hall–Petch behavior. Above 21&#xa0;nm, dislocation activity becomes the primary deformation mechanism. This study reveals that gradient nanograined outperform homogeneous nanograined (HNG) in all mechanical properties. The deformation mechanisms of GNG γ-TiAl alloys involve dislocation glide, with Lomer–Cottrell locks forming in large grains to impede stacking fault propagation and enhance material strength. GNG γ-TiAl alloys exhibit extra strain hardening due to strain gradients induced by grain size variations, which promote dislocation multiplication and generate unique multiaxial stress states. This study reveals the deformation mechanism of GNG γ-TiAl alloys and provides guidance for further improving the mechanical properties of TiAl alloys.</p>

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Gradient Structure Induced Strengthening Mechanisms in Polycrystalline TiAl Alloys

  • 期刊论文

  • 发表日期：

    2026年6月1日

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  • Juntao Zhou,
  • Shiping Wang,
  • Linfeng Qiu,
  • Xiong Zhou,
  • Lei Sheng,
  • Sihai Deng,
  • Zhenchuan Zhang,
  • Gang Chen,
  • Wenjuan Li,
  • Pengcheng Zhai,
  • Guodong Li

摘要

TiAl alloys, as a new generation of lightweight high-temperature materials, exhibit significant application potential in aerospace engines and related advanced propulsion systems. Gradient structures represent an effective strategy for manufacturing metals with superior mechanical properties. However, the deformation mechanisms of gradient nanograined (GNG) γ-TiAl alloys remain incompletely understood. In this work, we investigated the effects of different grain sizes and gradient structures on the uniaxial tensile deformation behavior of γ-TiAl alloys using molecular dynamics simulation methods. The results indicate that the peak strength occurs at a critical grain size of 21 nm. Below 21 nm, grain boundary migration and grain rotation dominate as the primary deformation mechanisms governing the inverse Hall–Petch behavior. Above 21 nm, dislocation activity becomes the primary deformation mechanism. This study reveals that gradient nanograined outperform homogeneous nanograined (HNG) in all mechanical properties. The deformation mechanisms of GNG γ-TiAl alloys involve dislocation glide, with Lomer–Cottrell locks forming in large grains to impede stacking fault propagation and enhance material strength. GNG γ-TiAl alloys exhibit extra strain hardening due to strain gradients induced by grain size variations, which promote dislocation multiplication and generate unique multiaxial stress states. This study reveals the deformation mechanism of GNG γ-TiAl alloys and provides guidance for further improving the mechanical properties of TiAl alloys.