Al/Al 2 O 3 metal matrix composites produced using magnetic field-assisted freeze-casting of porous ceramic structures

Al/Al 2 O 3 metal matrix composites (MMCs) were produced by metal infiltration of porous ceramic preforms. The porous ceramic preforms were fabricated using the magnetic field-assisted freeze-casting method, resulting in vertically aligned porous channels. Preforms were prepared by freezing an Al 2 O 3 /Fe 3 O 4 -containing slurry within an applied magnetic field. Vertical alignment of the channels was facilitated by the magnetic response of the Fe 3 O 4 in the slurry during the freezing process. After freezing and sublimation, the ceramic preforms were sintered and then infiltrated with molten A356 Al-based alloy. The mechanical properties of the resulting Al 2 O 3 /A356 MMCs were compared to those of bulk Al 2 O 3 , bulk Al-based alloy (A356), and porous Al 2 O 3 preforms using micro-indentation testing. The indentation hardness and elastic moduli values of Al 2 O 3 /A356 MMCs showed good agreement with the predicted theoretical calculations. This study provides a new approach for the design of MMCs with controlled composition and improved mechanical characteristics. Graphic abstract