Mechanical and Thermal Expansion Properties of SiCp/ZAlSi9Mg Composites Produced by Centrifugal Casting

Centrifugal casting was applied to produce cylindrical castings using SiCp/Al composite slurry, which contained 20% SiC particles. The castings comprised a particle free zone and a particle rich zone. The amount of SiC particles had a dramatic transformation from the particle rich zone to the particle free zone, and the maximum content of SiC particles in the particle rich zone reached up to 40 vol%. The ultimate tensile strength (UTS) of the as-cast SiCp / Al composites in the particle rich zone was 143 MPa, and the fracture was caused by the desorption of SiC particles from matrix alloy. The coefficient of thermal expansion (CTE) of the SiCp / Al composites in the range of 20 and 100 degrees C was determined as 16.67x10(-6) s(-1), and the experimental CTE was lower than the predicted data based on the Kerner's model. The results show that the decrease in CTE in the case of the composites at high temperature stage can be attributed to the solute concentration of Si in Al and the plastic deformation of the matrix alloy in the composites with void architecture.