Alumina-based interpenetrating phase composites by binder jetting: effects of powder multimodal distributions on porous preforms formation and copper-infiltrated composite performance

The development of interpenetrating phase composites via binder jetting offers a promising route for fabricating architected ceramic–based systems with tailored microstructures and multifunctional properties. This study investigates the influence of multimodal particle size distributions of spheroidized alumina powders on the formation, sintering behaviour, and copper infiltration performance of porous ceramic preforms. Six distinct feedstocks with varying multimodality were characterized in terms of flowability, spreadability, and packing efficiency. The resulting green and sintered preforms were evaluated for porosity morphology and densification kinetics by geometrical measurements and computed tomography, revealing feedstock-dependent voids architectures. These networks control capillary-driven infiltration dynamics and the formation of complex copper–alumina oxide phases, including spinel and delafossite with twinning mechanisms. CALPHAD simulations corroborated the experimental findings, elucidating the thermodynamic pathways of phase evolution under varying oxygen activities. Mechanical testing demonstrated that composites derived from sintered preforms exhibit superior hardness and wear resistance with a reduction of the friction coefficient of ∼25 % compared to those produced from green preforms, attributed to enhanced alumina content and refined oxide phase distribution. These results underscore the pivotal role of powder multimodality and preform processing in dictating the hierarchical structure and performance of printed ceramic–based composites, offering new insights for the design of advanced materials with tunable properties and complex geometries.