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<p>The in-situ synthesis of ceramic reinforcing phases during additive manufacturing is an effective route to fabricate high-performance Ti-6Al-4&#xa0;V composites. However, the conventional Gaussian laser (GL) directed energy deposition (DED) process is often limited by the induced growth of coarse columnar grains and the agglomeration of the reinforcing phase. This study proposes a novel approach for modulating the in-situ reaction of nano-sized boron nitride using a circular oscillating laser (COL) technique. A systematic comparison was conducted between this technique and the conventional Gaussian laser process in fabricating pure Ti-6Al-4&#xa0;V and its composite counterpart reinforced with 0.4 wt% nano-sized boron nitride. The results reveal a significant synergistic effect between the COL process and BN addition on both microstructural refinement and mechanical property enhancement. The COL process effectively suppresses the growth of columnar grains. Concurrently, it facilitates the formation of a fine, continuous network composed of in-situ synthesized nano-scale TiB whiskers along the grain boundaries. Compared with the GL-DED samples, the BN/TC4 composites fabricated by the COL-DED process exhibited an approximately 17.3% reduction in average grain size, a 33.7% increase in average microhardness, and a 31.9% decrease in wear loss. The performance improvement can be attributed to the intense melt pool stirring and thermal convection induced by the oscillating laser, which not only promoted the uniform dispersion and nucleation of in-situ TiB whiskers, but also altered the solute distribution behavior and crystal growth mode during solidification, thereby achieving microstructural refinement and multi-mechanism synergistic strengthening.</p> Graphical abstract <p></p>

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Enhanced Wear Resistance of In-situ TiB-Reinforced Titanium Composites through Microstructural Refinement via Circular Oscillating Laser Deposition

  • 期刊论文

  • 发表日期：

    2025年12月5日

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  • Junsong Wang,
  • Jianbo Lei,
  • Chao Wang,
  • Yan Fang,
  • Xiaohui Jia,
  • Jindong Huang

摘要

The in-situ synthesis of ceramic reinforcing phases during additive manufacturing is an effective route to fabricate high-performance Ti-6Al-4 V composites. However, the conventional Gaussian laser (GL) directed energy deposition (DED) process is often limited by the induced growth of coarse columnar grains and the agglomeration of the reinforcing phase. This study proposes a novel approach for modulating the in-situ reaction of nano-sized boron nitride using a circular oscillating laser (COL) technique. A systematic comparison was conducted between this technique and the conventional Gaussian laser process in fabricating pure Ti-6Al-4 V and its composite counterpart reinforced with 0.4 wt% nano-sized boron nitride. The results reveal a significant synergistic effect between the COL process and BN addition on both microstructural refinement and mechanical property enhancement. The COL process effectively suppresses the growth of columnar grains. Concurrently, it facilitates the formation of a fine, continuous network composed of in-situ synthesized nano-scale TiB whiskers along the grain boundaries. Compared with the GL-DED samples, the BN/TC4 composites fabricated by the COL-DED process exhibited an approximately 17.3% reduction in average grain size, a 33.7% increase in average microhardness, and a 31.9% decrease in wear loss. The performance improvement can be attributed to the intense melt pool stirring and thermal convection induced by the oscillating laser, which not only promoted the uniform dispersion and nucleation of in-situ TiB whiskers, but also altered the solute distribution behavior and crystal growth mode during solidification, thereby achieving microstructural refinement and multi-mechanism synergistic strengthening.

Graphical abstract