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<p>The phase transformation and mechanical behavior of Ti–43Al–9V–0.2Y alloy under varied heat treatments were systematically investigated. The cooling phase sequence is identified as β → β + α → α → γ + α (α<sub>2</sub>) → β + γ + α (α<sub>2</sub>) → β (β<sub>0</sub>) + γ. Above 1240&#xa0;°C, slow cooling forms lamellar structures via α → γ + α (α<sub>2</sub>) → β + γ + α (α<sub>2</sub>), while fast cooling follows α → γ + α → β (β<sub>0</sub>) + γ; below 1240&#xa0;°C, α → γ + α (α<sub>2</sub>) dominates. At 800&#xa0;°C and 1.0 × 10<sup>−4</sup>&#xa0;s<sup>−1</sup>, γ phase in duplex microstructures restricts dislocation slip due to low stacking fault energy, promoting dynamic recrystallization. Mixed microstructure (γ/β<sub>0</sub> lamellar and duplex microstructure) achieves a remarkable strength-ductility product of 4907&#xa0;MPa% through synergistic effects: the duplex enhances plasticity, while the lamellar improves strength. In both microstructures, limited dislocation slip/climb in β<sub>0</sub> phases creates dislocation density gradients at γ/β<sub>0</sub> interfaces, inducing micro-void nucleation and microcracks in β<sub>0</sub>. γ phase impedes defect propagation, and micro-voids further suppress crack growth. The crack propagation in α<sub>2</sub>/γ lamellar microstructure depends on stress direction: parallel stress hinders crack initiation and growth, while perpendicular stress promotes crack nucleation and expansion.</p>

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Effect of heat treatment parameters on microstructure evolution and high-temperature mechanical properties of Ti–43Al–9V–0.2Y rolled plates

  • 期刊论文

  • 发表日期：

    2026年1月9日

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  • Yang-Jie Gao,
  • Hai-Tao Jiang,
  • Shi-Wei Tian,
  • Si-Yuan Zhang,
  • Zhi-Chao Zhu

摘要

The phase transformation and mechanical behavior of Ti–43Al–9V–0.2Y alloy under varied heat treatments were systematically investigated. The cooling phase sequence is identified as β → β + α → α → γ + α (α2) → β + γ + α (α2) → β (β0) + γ. Above 1240 °C, slow cooling forms lamellar structures via α → γ + α (α2) → β + γ + α (α2), while fast cooling follows α → γ + α → β (β0) + γ; below 1240 °C, α → γ + α (α2) dominates. At 800 °C and 1.0 × 10−4 s−1, γ phase in duplex microstructures restricts dislocation slip due to low stacking fault energy, promoting dynamic recrystallization. Mixed microstructure (γ/β0 lamellar and duplex microstructure) achieves a remarkable strength-ductility product of 4907 MPa% through synergistic effects: the duplex enhances plasticity, while the lamellar improves strength. In both microstructures, limited dislocation slip/climb in β0 phases creates dislocation density gradients at γ/β0 interfaces, inducing micro-void nucleation and microcracks in β0. γ phase impedes defect propagation, and micro-voids further suppress crack growth. The crack propagation in α2/γ lamellar microstructure depends on stress direction: parallel stress hinders crack initiation and growth, while perpendicular stress promotes crack nucleation and expansion.