Ceramic particle-reinforced metal matrix composites (MMCs) have attracted wide interest across multiple industries because they combine the ductility and toughness of metals with the hardness, stiffness, and thermal stability of ceramics. In recent years, additive manufacturing (AM) has emerged for producing MMCs with complex geometries and functionally graded structures. Among AM technologies, directed energy deposition (DED) offers exceptional flexibility in material feedstock control, making it suitable for fabricating MMCs ranging from protective coatings to complex bulk components. Although DED has been successfully employed to manufacture a wide range of ceramic particle-reinforced MMC systems, achieving uniform particle dispersion remains a major scientific and technological challenge. Reinforcement particles often segregate due to density mismatch and complex melt-pool fluid flow, resulting in heterogeneous microstructures and reduced mechanical reliability. This Engineering Research Initiation (ERI) project aims to uncover the fundamental mechanisms governing three-dimensional (3D) particle dispersion during DED and to identify manufacturing conditions that promote uniform particle distribution. The outcomes will advance the scientific foundation of additive manufacturing and strengthen the United States’ capability to produce high-performance materials for critical industries including aerospace, energy, and defense. This research will also contribute to education and workforce development by involving undergraduate and graduate students in research activities, integrating additive manufacturing experiments into engineering courses, and engaging K-12 students through outreach programs. The technical objective of this work is to establish a mechanism-guided framework for controlling the three-dimensional dispersion of micro-scale ceramic reinforcements in directed energy deposition of metal matrix composites. The research integrates controlled experiment