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<p>Understanding how hydrogen-assisted pore formation affects microstructure and performance remains a critical challenge in LPBF-fabricated porous titanium alloys. In particular, the interaction between hydrogen evolution from TiH₂, melt-pool dynamics, and phase transformation is not yet fully clarified. In this work, TiH₂ was incorporated into Ti6Al4V powder (2–10 wt%) as an in-situ foaming agent, and the combined effects of TiH₂ content, laser power, and scanning speed on pore architecture, microstructure, and corrosion behavior were systematically investigated. Multiscale characterization (OM, CT, SEM, EBSD, XRD, and electrochemical testing) was used to track pore evolution and structural transitions. Increasing TiH₂ content promoted hydrogen release and entrapment, increasing porosity and shifting pore morphology from isolated spherical pores to partly interconnected channels aligned with the build direction. TiH₂ addition refined acicular α′ martensite, disrupted β grain continuity, and weakened crystallographic texture, while concurrently increasing surface roughness and significantly reducing corrosion resistance. A processing window based on volumetric energy density was established to mitigate lack-of-fusion defects while regulating hydrogen-assisted porosity. These findings elucidate the mechanisms governing pore formation and microstructural evolution in TiH₂-assisted LPBF.</p>

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Pore formation mechanisms and microstructural evolution in LPBF-fabricated Ti6Al4V with TiH₂ foaming agents

  • 期刊论文

  • 发表日期：

    2026年3月2日

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  • Kai Liu,
  • Hankun Zhu,
  • Zihui Yu,
  • Tian Yang,
  • Wei Han,
  • Lingbao Kong

摘要

Understanding how hydrogen-assisted pore formation affects microstructure and performance remains a critical challenge in LPBF-fabricated porous titanium alloys. In particular, the interaction between hydrogen evolution from TiH₂, melt-pool dynamics, and phase transformation is not yet fully clarified. In this work, TiH₂ was incorporated into Ti6Al4V powder (2–10 wt%) as an in-situ foaming agent, and the combined effects of TiH₂ content, laser power, and scanning speed on pore architecture, microstructure, and corrosion behavior were systematically investigated. Multiscale characterization (OM, CT, SEM, EBSD, XRD, and electrochemical testing) was used to track pore evolution and structural transitions. Increasing TiH₂ content promoted hydrogen release and entrapment, increasing porosity and shifting pore morphology from isolated spherical pores to partly interconnected channels aligned with the build direction. TiH₂ addition refined acicular α′ martensite, disrupted β grain continuity, and weakened crystallographic texture, while concurrently increasing surface roughness and significantly reducing corrosion resistance. A processing window based on volumetric energy density was established to mitigate lack-of-fusion defects while regulating hydrogen-assisted porosity. These findings elucidate the mechanisms governing pore formation and microstructural evolution in TiH₂-assisted LPBF.