Alumina–Nickel Composite Processed via Co-Assembly Using Freeze-Casting and Spark Plasma Sintering

A metal–ceramic composite comprised of ≈82 vol% alumina (Al ₂ O ₃ ) and ≈18 vol% nickel (Ni) is fabricated via co-assembly of alumina micro-platelets with Ni particles using the freeze-casting process followed by the spark plasma sintering (SPS). The SPS processing with a custom-designed temperature-pressure history result in formation of elongated Ni phase between the lamellar-ceramic phase. Results of the mechanical characterization shows that inclusion of Ni improves the flexural strength of the composite by more than 47% compared to the lamellar ceramic. Additionally, the crack initiation (K _IC ) and crack growth toughness increase by 20% and 47%, respectively. The inclusion of softer Ni phase does not compromise the indentation modulus and indentation hardness of the composite compared to the pure ceramic.