Consolidation of aluminum-based metal matrix composites via spark plasma sintering

Aluminum-based metal matrix composite (MMC) materials containing SiC, AlN, Si3N4 or BN were processed by spark plasma sintering (SPS). Ceramic powder type, size and content were investigated to determine their effect on sinter quality. SiC, AlN and Si3N4 proved to be amenable to this style of processing whereas all systems containing BN were not. Full densification of MMCs that incorporated finer ceramic particles was problematic due to the presence of ceramic clusters and the extent to which aluminum could be forced into these regions. MMCs that incorporated coarser ceramic particles were more easily densified, but their hardness benefits were inferior. Three point bend tests proved to be an effective tool in determining the relative sinter quality of MMC systems. SiC outperformed AlN MMC samples in bend tests. Excellent ductility and bend strength was developed at low temperatures, while equivalent AlN-bearing materials required significantly higher temperatures to achieve comparable properties.