Enhanced 3D printing in large-size Al₂O₃/GdAlO₃/ZrO₂ eutectic ceramics directly by laser directed energy deposition based on an oscillation process

Despite its promise for fabricating complex, high-performance oxide eutectic ceramics with ultra-fine microstructures, laser directed energy deposition (LDED) is hindered by the intrinsic brittleness of ceramics, which causes cracking during rapid solidification. This paper explores the integration of the oscillation forming process into the LDED technique for Al₂O₃/GdAlO₃/ZrO₂ ternary eutectic ceramics to suppress cracking. The influence of oscillation parameters on the forming quality and microstructure of ceramic samples was investigated. A processing parameter window was identified for fabricating eutectic ceramics with high relative density and minimal cracking. The oscillation process enhanced overall microstructural homogeneity and promoted the formation of equiaxed eutectic colonies. Additionally, the energy distribution within the melt pool during the oscillation process, which was higher at the ends and lower in the center, effectively alleviated the problem of energy concentration during the non-oscillation process. More importantly, the oscillation process produced a stable melt zone of 5.5–7.0 mm with a unit deposition time of 2.0–2.46 s, achieving an effect similar to layer-by-layer deposition under preheating. Based on improved strain distribution across grain boundaries and reduced thermal stress, this study enabled the successful fabrication of large-sized rod-like, bulk, and frame-shaped eutectic ceramics, achieving continuous and stable deposition in three dimensions. These findings establish a new theoretical and technical basis for producing large, complex oxide eutectic ceramics and controlling solidification defects in laser additive manufacturing.