Post-Processing of Stir Casted Al–Si12Cu Metal Matrix Composite by Friction Stir Processing

In the present study friction stir processing is applied on the stir casted metal matrix composite as a post-processing operation. Stir casted metal matrix composites are prepared by using zircon sand particles of 40 µm in the matrix of Al–Si12Cu alloy. Friction stir processing is applied on the metal matrix plates at a constant rotational speed and traverse speed of 1400 rpm and 63 mm/min, respectively. Multiple passes of friction stir processing are applied to elucidate the effect of number of passes on microstructural modification. Microstructural examination showed a significant improvement in eutectic silicon morphology and distribution of zircon sand particles. After four passes of friction stir processing the zircon sand particles are reduced to ~5 µm as compared to initial size of ~40 µm. The friction stir processed metal matrix composite exhibited an increase in ultimate tensile strength, yield strength, percentage elongation, and hardness by ~90, ~104, ~300, and ~34%, respectively as compared to cast metal matrix composite.