Microstructural aspects of ceramic hollow microspheres reinforced metal matrix composites

Abstract

Abstract Ceramic hollow microsphere reinforced metal matrix syntactic foams were produced by means of pressure infiltration. The reinforcing ceramic hollow microsphere's (SL300) microstructure was investigated. The microspheres contained various oxide ceramics, mainly Al2O3 and SiO2. The samples were characterized using X-ray diffraction measurements and energy dispersive spectroscopy maps. The results showed that the Al2O3 and SiO2 distribution in the wall of the microspheres is not equal; Al2O3 needles are embedded in the surrounding mullite and SiO2 phase. Line energy dispersive X-ray spectroscopy measurements showed that, due to the above mentioned uneven distribution of Al2O3 rich particles, a chemical exchange reaction took place between the aluminium alloy matrix and the microspheres and because of that the wall of the hollow microspheres became damaged.