Variations in processing, microstructure and properties of Al/Al_{2O_{3 composites fabricated by displacement reaction

In order to supply variations in mechanical properties to Al/Al2O3 composites by displacement reaction between Si O2 and molten Al, two processes were attempted to fabricate the modified composites. The first process was to infiltrate Al melt into a partially sintered Si O7 preform and Al/Al2O3 composites were obtained. Molten Al infiltrated into some pores in the preform, which formed thick Al channels in the composite bodies. The mechanical property changed from dutile to brittle, depending on the thickness of these Al channels, which was related to the sintering temperature of Si O2 preforms. Al-Cu/Al/Al2O2 composites were fabricated by reaction between molten Al-Cu alloy and Si O2. The hardness increased 1.5 times by aging the specimens. Fine precipitates were observed in Al parts in the composite bodies. Their mechanical properties were discussed in relation with the microstructures.