Characterization of micro and nano two-phase regimes created by explosive shock-wave consolidation of powder mixtures

Mechanically mixed Al powders (150 μm in diameter) and different combinations of 21% volume fraction of SiC or Al2O3, (30 μm or 30 nm particle sizes) were green compacted to 70% density. The compactions were explosively consolidated in cylindrical fixtures utilizing ammonium nitrate-fuel oil (ANFO) to fabricate stacks of two-phase, cylindrical monoliths 50 mm × 32 mm (diameter), along with pure aluminum (Al-1100) monoliths (as reference). Results show that the consolidated aluminum increases from a starting powder hardness of 24 HV to 46 HV. Correspondingly, hardness for the two-phase systems exhibits an increment by ∼ 60% from the reference SWC Al-1100, while the total elongation declined by ∼ 60%. Microstructures for these systems were also observed by optical metallography and TEM to exhibit the different second phasesʹ consolidation and its effect on the fracture mechanisms. Images presented show the different rupture mechanisms observed from the different systemsʹ samples; the aluminum ductile-dimple fracture, the intergranular debonding caused by the micron-sized ceramic second phase and the quasicleavage and transgranular fractures caused by the nano-ceramic second phase.