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<p>The β<sub>trans</sub> (β transformed microstructure) of a bimodal Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy was refined via high strain rate (~ 13.5&#xa0;s<sup>− 1</sup>) forging at 900&#xa0;°C followed with duplex aging (350&#xa0;°C/1.5, 2, 2.5&#xa0;h + 600&#xa0;°C/2.5&#xa0;h) treatments. The microstructure evolutions, mechanical properties and deformation mechanisms of alloy suffering this processing were studied in detail. Results show that the forging deformation promotes the α→β transformation, dynamic recrystallization and dislocation multiplication of β phase. The yield strength (<i>σ</i><sub>0.2</sub>) and ultimate tensile strength (<i>σ</i><sub>b</sub>) of as-forged alloy are lower than the as-received alloy (<i>σ</i><sub>0.2</sub>:1073 MPa, <i>σ</i><sub>b</sub>:1134&#xa0;MPa), but the elongation (<i>δ</i>) is increased (maximum to 24%). The decreased strength of as-forged alloy is attributed to the α<sub>s</sub> to β phase transformation while the higher ductility is caused by multiple dislocation slipping and plastic extension of β phase, together with the elongation and &lt; 11–20 &gt; twin activation of α<sub>p</sub>. After duplex aging, the initial β<sub>trans</sub> of as-received alloy is refined greatly due to the nano-scale α<sub>s</sub> precipitation, in which the alloy aged at 350&#xa0;°C/1.5&#xa0;h + 600&#xa0;°C/2.5&#xa0;h displays the <i>σ</i><sub>0.2</sub>, <i>σ</i><sub>b</sub> and <i>δ</i> of 1466&#xa0;MPa,1503&#xa0;MPa and 5.9% respectively. The α/β phase interface strengthening is the dominated strengthening mechanism of β<sub>trans</sub> refined alloy and the limited dislocation strengthening is also helpful. The shorter soaking time at 350&#xa0;°C results to more homogeneous α<sub>s</sub> precipitation in β<sub>trans</sub>, which are attributed to the dispersed dislocations in β phase, ω/β interface assisted nucleation and β phase separation.</p> Graphical Abstract <p></p>

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Enhancing Mechanical Properties of Bimodal Ti-5Al-2Sn-2Zr-4Mo-4Cr Alloy Via Hot Deformation Plus Duplex Aging Induced βtrans Refinement

  • 期刊论文

  • 发表日期：

    2025年10月27日

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  • Yangbo Yu,
  • Hongge Yan,
  • Jihua Chen,
  • Weijun Xia,
  • Bin Su,
  • Jialong Fu,
  • Min Song

摘要

The βtrans (β transformed microstructure) of a bimodal Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy was refined via high strain rate (~ 13.5 s− 1) forging at 900 °C followed with duplex aging (350 °C/1.5, 2, 2.5 h + 600 °C/2.5 h) treatments. The microstructure evolutions, mechanical properties and deformation mechanisms of alloy suffering this processing were studied in detail. Results show that the forging deformation promotes the α→β transformation, dynamic recrystallization and dislocation multiplication of β phase. The yield strength (σ0.2) and ultimate tensile strength (σb) of as-forged alloy are lower than the as-received alloy (σ0.2:1073 MPa, σb:1134 MPa), but the elongation (δ) is increased (maximum to 24%). The decreased strength of as-forged alloy is attributed to the αs to β phase transformation while the higher ductility is caused by multiple dislocation slipping and plastic extension of β phase, together with the elongation and < 11–20 > twin activation of αp. After duplex aging, the initial βtrans of as-received alloy is refined greatly due to the nano-scale αs precipitation, in which the alloy aged at 350 °C/1.5 h + 600 °C/2.5 h displays the σ0.2, σb and δ of 1466 MPa,1503 MPa and 5.9% respectively. The α/β phase interface strengthening is the dominated strengthening mechanism of βtrans refined alloy and the limited dislocation strengthening is also helpful. The shorter soaking time at 350 °C results to more homogeneous αs precipitation in βtrans, which are attributed to the dispersed dislocations in β phase, ω/β interface assisted nucleation and β phase separation.

Graphical Abstract