SOLIDIFICATION BEHAVIOR OF AI-Li-SiCpMMCs PROCESSED USING VARIABLE CO-DEPOSITION OF MULTI-PHASE MATERIALS

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Abstract
In the present study, the effect of matrix solidification on the resulting size and distribution of SiC particulates during spray atomization and co-deposition was investigated. The microstructure of the spray deposited materials was characterized as a function of cross-sectional thickness for a single experiment, as well as for different processing variables for distinct experiments. In order to assess the effect of SiC particulates on the microstructural evolution during processing, the unreinforced Al-Li material was also studied. Regarding the interaction of SiC particulates with the solidification front, the present results show that the kinetic and thermodynamic models commonly used to describe the behavior of ceramic particulates during solidification do not give adequate results when applied to the conditions present during spray atomization and deposition. Instead, an alternate criterion based on mechanically driven engulfment during spray atomization and deposition is proposed. The microstructural studies were accomplished using scanning microscopy, optical microscopy and image analysis. Finally, the observed microstructural features and the computed thermal and solidification conditions of the atomized matrix are discussed concurrently.