Infiltration Kinetics and Interfacial Bond Strength of Metal Matrix Composites.

摘要

The research accomplishments for this three-year metal matrix composite research program centered upon three areas: infiltration kinetics, wettability studies and predictions of interfacial properties. A pre-conditioning reaction model was hypothesized to explain the incubation period observed to precede the liquid metal infiltration of SiC particulate, and a rate equation for pre-conditioning was experimentally established for the infiltration of SiC particulate by liquid aluminum. Experimental wettability studies were completed for aluminum--silicon, aluminum--magnesium, and aluminum--lithium alloys in contact with SiC by utilizing a capillary rise apparatus. The oxide layers on the ceramic substrate and on the molten metal surface were observed to strongly influence wetting behavior. Differential optical reflectance was used to measure the optical transitions in aluminum and its alloys. Interfacial bond energies were estimated using a work of decohesion model. Punch shear tests then provided relative estimates of bond strengths for several aluminum alloys in contact with silicon carbide. Concepts from surface science and thermodynamics were coupled to theoretically predict wettability. Wetting was treated as a surface phenomenon, in which a surface reaction monolayer was sufficient to cause wetting. Aluminum matrix composite processing using the liquid metal route is complicated by the oxide barrier formed on the liquid metal. A transport model was used to explain the observed interfacial reaction behavior.