Stir casting process setup is shown in Figure 1. In a stir casting process, the reinforcing phases (usually in
powder form) are distributed into molten aluminium by mechanical stirring. Prior to mechanical stirring, the
surfaces of both must be properly cleaned in order to minimize the reaction between these two. Introducing
reinforcement particles to the stirred molten matrix sometimes will entrap not only the particles but also other
impurities such as metal oxide and slag, which is formed on the surface of the melt. During pouring, air envelopes
may form between particles, which can alter the interface properties between particles and the melt, and also
retarding the wettability between them. A major concern associated with the stir casting process is the segregation of
reinforcing particles which is caused by the surfacing or settling of reinforcement particles during melting and
casting process. To prevent settling of particles a motor driven agitator is used. Aluminium silicon carbide metal
matrix composite will reach a state called mushy state before solidification. Once the mushy state is reached the
reinforcement particles remain in its position during solidification. The final distribution of the particles in the solid
depends on material properties and process parameters such as the wetting condition of the particles with the melt,
strength of mixing, relative density, and rate of solidification. The distribution of the particles in the molten matrix
also depends on the geometry of the mechanical stirrer, stirring parameters, placement of the mechanical stirrer in
the melt, melting temperature, and the characteristics of the particles added. To create and maintain a good
distribution of the reinforcement material in molten matrix a vortex method is used. In this method, after the matrix
material is melted, it is stirred vigorously to form a vortex at the surface of the melt, and the reinforcement material
is then introduced at the side of the vortex. The stirring is continued for a few minutes before the slurry is cast [5].reinforcement particles, different researchers have used varying temperature and time (10000C for 1.5h in air [7],
11000C for 1-3h [8], 8500C for 8h [9]). Preheating of reinforcement particles prevents the reaction between matrix
and reinforcement. Further, preheating of SiC particles assists in removing surface impurities, and altering the
surface composition due to formation of SiO2 layer on the surface.