Microstructure evolution during near-net-shape fabrication of NixAly-TiC cermets through binder jet additive manufacturing and pressureless melt infiltration

Titanium carbide-nickel aluminide (TiC-NixAly) intermetallic matrix composite materials were fabricated with additive manufacturing and pressureless melt infiltration for applications intended for high-wear and corrosive environments while maintaining low density. Here, two compositions of nickel aluminide are infiltrated into porous, printed TiC preforms. Net shaping of a nickel-rich infiltrant is less compared to the net shaping of the aluminum-rich infiltrant due to dissolution of TiC in the molten infiltrant. The microstructures and porosity of the two infiltrants with TiC are examined after processing. The explanation of shape retention from infiltration is explained, and the excellent shape retention in an Al-rich infiltrant system is thought to be from peritectic behavior and a metered infiltration of different phases during cooling and solidification without significant dissolution. The metered infiltration contributed to some porosity, microcracking, and segregated NixAly phases. This work demonstrates that TiC can be shaped and infiltrated with intermetallics to provide a method of making composites with limited shrinkage and controlled geometry.