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<p>The isothermal oxidation behavior of a TC30-1 titanium alloy (Ti-3.3Al-2.8Mo-1.2&#xa0;V, wt%) was investigated in air at 800-1000&#xa0;°C for 0.5-3&#xa0;h. Mass gain shows a brief rapid uptake (~1&#xa0;h) followed by near-parabolic kinetics; the parabolic rate constant rises steeply with temperature. X-ray diffraction identifies rutile (TiO<sub>2</sub>) as the dominant phase; EDS reveals minor Al-rich oxides and trace V oxides at particle boundaries. SEM shows a rutile-based scale that coarsens with time and temperature: porosity becomes pervasive and microcracks appear at 1000&#xa0;°C, indicating loss of integrity. These features reflect vacancy supersaturation from unbalanced outward Ti/Al fluxes and inward oxygen (Kirkendall porosity), compounded by growth and thermal-mismatch stresses. Cross-sections reveal an oxygen-enriched α-case beneath the scale under all conditions; it thickens with temperature/exposure and exhibits a wavy interface that follows the prior lamellar morphology, consistent with diffusion-controlled oxygen ingress into α + β Ti. Compared with Ti-6Al-4&#xa0;V (α-case often &gt; 20&#xa0;µm), TC30-1 forms a thinner α-case (&lt;10&#xa0;µm), attributed to higher β-stabilizer (Mo/V) levels that lower effective oxygen diffusivity and reduce the dissolution driving force. Overall, coupled outward metal diffusion and inward oxygen transport govern scale growth, while vacancy coalescence and evolving stresses generate porosity and cracking—effects that intensify at 1000&#xa0;°C.</p>

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Isothermal Oxidation Kinetics and Rutile-Based Scale Integrity of the TC30-1 Titanium Alloy at 800-1000 °C: Diffusion-Controlled Growth and α-case Development in Air

  • 期刊论文

  • 发表日期：

    2026年4月22日

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  • Kai Tang,
  • Bobo Lu,
  • Qihong Li,
  • Gang Yang,
  • Junming Fan,
  • Qixiong Zhou,
  • Wei Wei

摘要

The isothermal oxidation behavior of a TC30-1 titanium alloy (Ti-3.3Al-2.8Mo-1.2 V, wt%) was investigated in air at 800-1000 °C for 0.5-3 h. Mass gain shows a brief rapid uptake (~1 h) followed by near-parabolic kinetics; the parabolic rate constant rises steeply with temperature. X-ray diffraction identifies rutile (TiO2) as the dominant phase; EDS reveals minor Al-rich oxides and trace V oxides at particle boundaries. SEM shows a rutile-based scale that coarsens with time and temperature: porosity becomes pervasive and microcracks appear at 1000 °C, indicating loss of integrity. These features reflect vacancy supersaturation from unbalanced outward Ti/Al fluxes and inward oxygen (Kirkendall porosity), compounded by growth and thermal-mismatch stresses. Cross-sections reveal an oxygen-enriched α-case beneath the scale under all conditions; it thickens with temperature/exposure and exhibits a wavy interface that follows the prior lamellar morphology, consistent with diffusion-controlled oxygen ingress into α + β Ti. Compared with Ti-6Al-4 V (α-case often > 20 µm), TC30-1 forms a thinner α-case (<10 µm), attributed to higher β-stabilizer (Mo/V) levels that lower effective oxygen diffusivity and reduce the dissolution driving force. Overall, coupled outward metal diffusion and inward oxygen transport govern scale growth, while vacancy coalescence and evolving stresses generate porosity and cracking—effects that intensify at 1000 °C.