"Additive Manufacturing of Alumina via Laser Powder Bed Fusion: Defect Formation Mechanisms and Mitigation Strategies" 

Sodiq Abiodun Kareem, MSE PhD Candidate 

Advisor: Professor Xinghang Zhang

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Alumina is valued for its high chemical stability, high temperature resistance, and biocompatibility, enabling widespread use in aerospace, electronics, and biomedical applications. However, conventional processing methods struggle to produce complex geometries and often require expensive molds and tooling. Laser Powder Bed Fusion (LPBF), an additive manufacturing (AM) technique, presents a promising alternative by enabling layer-by-layer fabrication of intricate alumina components without molds. Despite its advantages, the LPBF process is challenged by alumina’s low laser absorptivity, intrinsic brittleness, and steep thermal gradients, which often result in defects such as porosity, microcracks, and macrocracks. This review outlines the fundamentals of LPBF for alumina, discussing the influence of powder characteristics, scanning strategies, and laser-material interactions. It explores the mechanisms behind defect formation, including thermal stress, shrinkage mismatch, and gas entrapment. Strategies to mitigate these issues are analyzed, including laser parameter optimization, build plate preheating, and the addition of dopants. Composition tuning, combined with control of laser parameters, has shown promise in improving density and mechanical performance. Mechanical testing reveals that optimizing laser parameters and thermal control can enhance hardness and toughness. While progress has been made, further work is needed in high-resolution defect analysis and mechanical validation to advance LPBF of alumina toward reliable industrial adoption.