Additive manufacturing has gained increasing interest to fabricate metal matrix composites. Particle agglomeration remains a critical challenge and can severely compromise the mechanical properties, in particular tensile ductility. Here we investigated and utilized laser powder-bed-fusion (L-PBF) to uniformly disperse particles in metal matrices, taking advantages of particle flow dynamics during melting and remelting. We demonstrate our approach in a TiB₂ reinforced aluminum system and produce a high dispersion of fine TiB₂ particles (with sizes down to tens of nanometers) in a single print. Both micron- (1-5 μm) and nano-sized (40 nm) TiB₂ particles are found to be uniformly dispersed in composites, with a volume fraction of up to 25%. High-fidelity computer modeling indicates that although particles flow with Marangoni vortexes, the melt pool overlapping and subsequent re-melting/re-solidification play an important role for the successful dispersion. The propelling effect of vapor depression and particle filling via the Marangoni vortex flow are the two main mechanisms that lead to the uniform dispersion. A geometric criterion for hatch spacing is derived and verified by experiments for the successful uniform dispersion of reinforcing particles. Compared to composites with nonuniform particle dispersion, L-PBF aluminum 2024 composites show ∼30% higher tensile strength and ∼16% higher Young's modulus, together with a marked improvement of tensile ductility (up to three times higher). The uniform dispersion of reinforcing particles is also achieved in copper materials and thus demonstrates the versatility of our approach to other metals and alloys.

增材制造对制造金属基复合材料越来越感兴趣。颗粒团聚仍然是一个严峻的挑战，并且会严重损害机械性能，尤其是拉伸延展性。在这里，我们研究并利用激光粉末床熔合 (L-PBF) 在金属基体中均匀分散颗粒，利用熔化和重熔过程中的颗粒流动动力学。我们在 TiB ₂增强铝系统中展示了我们的方法，并在单次印刷中产生了高度分散的精细 TiB ₂颗粒（尺寸低至几十纳米）。微米 (1-5 μm) 和纳米 (40 nm) TiB ₂发现颗粒均匀分散在复合材料中，体积分数高达 25%。高保真计算机建模表明，尽管颗粒随 Marangoni 涡流流动，但熔池重叠和随后的再熔化/再凝固对成功分散起着重要作用。通过 Marangoni 涡流的蒸汽抑制和颗粒填充的推进作用是导致均匀分散的两个主要机制。为增强颗粒的成功均匀分散，推导并通过实验验证了舱口间距的几何标准。与颗粒分散不均匀的复合材料相比，L-PBF 铝 2024 复合材料的拉伸强度高出约 30%，杨氏模量高出约 16%，以及拉伸延展性的显着改善（高达三倍）。在铜材料中也实现了增强颗粒的均匀分散，从而证明了我们对其他金属和合金的方法的多功能性。