| On the basis of a general introduction to composite materials, this dissertation first reviews the research and development of ceramic matrix composites (CMCs) including their fabrications, engineering merits and potential applications. Among CMCs, ceramic matrix intermetallic bonded composites (CMICs) has been of the greatest importance for both ceramics and intermetallics, and are to date the most attracting high performance materials. The investigations on the CMICs at home and abroad including the fabrications, the microstructures and the mechanical properties are further comprehensively reviewed. Spontaneous (pressureless) infiltration of carbide powder compacts with intermetallic melts have been regarded as an interesting alternative to the preparations of CMICs. It has been employed in the fabrication of TiC matrix composites with Fe40Al and Ni3Al as binder. However, research in this regard is still primary and more intensive and extensive researches are needed in order to finally establish this fabrication technique in engineering.This dissertation has systematically investigated the fabrication of TiC matrix Fe-Al and Ni-Al intermetallics composites by spontaneous melt infiltration and the microstructure and properties of the composites. The wetting ability, the infiltration process and the infiltration kinetics of the liquid intermetallics in porous TiC preforms are the first concern of this study. Dense and defect-free composites have been obtained by optimizing the infiltration process including preform formation, relative density controlling, melt-feeding method and infiltration conditions. The composites were first characterized by microstructure observation and mechanical property measurements. The mechanical property measurements not only included room-temperature tests of bending strength, Vickers hardness, fracture toughness and Young's modulus, but also high temperature creep study, which is quite essential in the development of the CMICs for high temperature applications. This dissertation also pays its attention to the analyses and discussion on the microstructure evolution, the relationship between the microstructure and the properties, the strengthening mechanism and creep characteristics. The whole study involved most conventionalIVresearch method such as SEM, TEM, EDS, XRD and optical microscopy. The intermetallic bonded (TiC-TiN-WC) composite was also prepared by the spontaneous melt infiltration, and the Ti(CN)/(Ti,W)(CN) core-rim structure in the composites was investigated in terms of the formation condition.The results of the investigations firstly show that the wetting abilities of liquid Fe40Al, Fe28Al, NisAl and NiAl in porous TiC preforms are extremely good. The liquid intermetallics can completely infiltrate the TiC preforms with relative density as high as 70-90% to form fully dense composites. Both TiC particles and intermetallics have high thermal and chemical stability during the infiltration that the original TiC and the intermetallic are the only two phases in the composites. However, there was active reaction between liquid TiAl(CrNb) and TiC, and liquid TiAl(CrNb) couldn't completely infiltrate into porous TiC preform leaving high porosity in the composites. The amount of Fe40Al and Fe28Al infiltrated into the TiC preform can be far more than the pore volume of the preform showing an unique dilation infiltration behavior. The amount of Ni3 Al and NiAl infiltrated into the TiC preform has to be nearly equal to the pore volume of the preform.From kinetic point of view, the infiltration distance (depth) of Fe40Al melt in porous TiC prefrom follows a parabolic law of infiltration time. At the infiltrationtemperature of 1450癈, the infiltration distance (), the relative density of the TiC preform ( dr ) and the infiltration time ( / ) fit the following equation:h, =(94.5- 103.2dr) + (11.9- 7.3<)f2 or h, =A, -B,dr =The experimental parabolic coefficient of the infiltration distance (ll.9-7.3c,.) is lower than the estimated theoretical value...
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