Reaction sintering of intermetallic-reinforced composite materials

The goal of this research was to explore the powder metallurgy (P/M) processing response of materials based on the Al–Ni system. In doing so, compacts of pure aluminum powder as well as binary Al–Ni blends were prepared, compacted, sintered, and assessed. Research began with fundamental studies on the sintering response of the base aluminum powder. This system demonstrated a poor sintering response overall but did improve at higher temperatures commensurate with a small fraction of a secondary phase that was presumed to be aluminum nitride. In Al–Ni systems sintering temperature had a particularly pronounced effect on the resultant microstructure. At lower temperatures a composite of Al–NiAl₃–AlN was formed while higher temperatures yielded one of Al–NiAl₃ alone. It was postulated that the exothermicity of NiAl₃ formation and the extent of matrix sintering were controlling factors for this behaviour.