Enhanced densification of combustion synthesized Ni–Al intermetallic compound by Si addition

Ni–Al intermetallic compound was combustion synthesized from a powder mixture of elemental Al, Ni, and Si and was simultaneously bonded with spheroidal graphite cast iron substrate (FCD). By heating a powder mixture of elemental Al and Ni, exothermal reaction occurred at about 873 K to form Ni–Al intermetallic compound. However, the synthesized compound included a large volume of voids or unreacted regions. It was confirmed that Si addition as well as applying pressure were effective to decrease the voids or unreacted regions. It is considered that higher flowability of Al–Si liquid enhanced the densification of Ni–Al compound. The identification and growth behavior of the reaction layers formed in the interface between compound layer and FCD substrate was investigated.