Numerical simulation of solidification of reinforced metal matrix composites

The purpose of this research is to study the solidification process of squeeze casting for manufacturing fiber reinforced metal matrix composites (MMC). A two-dimensional numerical model describing the solidification process during the casting of MMC with thermal management of the reinforcement is developed based on the finite volume method. Some experiments were conducted in the Center for Composites in UWM to validate the numerical model.; Several numerical techniques involving the coupling of temperature and liquid fraction have been studied to test the computer code. A set of transport equations governing the solidification of a pure metal or a metallic alloy is presented. The numerical technique is applied to a range of solidification problems available from literature. These include the solidification process of liquid metal driven by pure heat conduction as well as by natural convection.; Following the demonstration of the accuracy of the numerical model, the solidification of MMC with the reinforcement, in the form of fiber, extending out of the mold and cooled by a heat sink is studied. The liquid metal is assumed to be confined in an insulated enclosure so that heat from the liquid melt is lost mainly to the cooled fiber. Some processing parameters such as the fiber diameter, fiber conductivity, the heat sink temperature, and the effect of natural convection within the liquid melt are studied.; Next, the solidification of MMC in squeeze casting is presented. This is different from the previous section in which high pressure is applied to the liquid melt and the effect of the mold is taken into consideration. A more comprehensive parametric study in squeeze casting is carried out which includes the effects of pouring temperature of the liquid melt, fiber diameter, fiber conductivity, fiber length extending out of the mold, heat sink temperature, mold conductivity, mold wall thickness, mold initial temperature, and applied pressure. Some of the computation results are validated by temperature profiles obtained from experimental measurements.; Finally, microstructures analyses have been conducted by the Materials Engineering Department at UWM to indicate the advantages of the current technique of having the reinforcement extending out of the mold and cooled by a heat sink. The microstructures show that primary alpha-aluminum grows radially outward from the surface of the reinforcement, and a major portion of the eutectic phase has been eliminated. This proves the feasibility of producing a new type of composite with improved material properties.