Abstract
Hybrid Al matrix composites reinforced with Kaowool ceramic fiber (Al2O3 · SiO2) and reaction formed intermetallic compound particles, starting compositions of (10%Al2O3 · SiO2 + 5%Ni)/Al and (10%Al2O3 · SiO2 + 5%TiO2)/Al were fabricated employing squeeze casting technique. Microstructures of the Al composites were examined, and the reactivity of Ni and TiO2 powders added to Kaowool short fiber preform with infiltrating molten Al, resulting products of Al3Ni and Al3Ti, during squeeze casting was analyzed. Hardness, strength (at 25 and 300°C) and wear resistance of the composites were characterized. To investigate the fracture behavior of the composites, in-situ fracture test was performed within SEM. The hybrid Al composites revealed the microstructure of uniformly distributed reinforcements (ceramic short fiber and reaction formed intermetallic compounds). Ni powder added hybrid Al composite achieved the highest hardness, strength and wear resistance among the composites. It was found that the strength drop at elevated temperature (300°C) is effectively reduced by hybridization with ceramic fiber and intermetallic compounds reinforced in Al. In-situ fracture observation demonstrated the fracture behavior of Ni powder added hybrid Al composite as microcrack initiated mainly by short fiber/ matrix interfacial debonding and the crack propagated through the cluster of intermetallic compound particles as loading is raised.
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