Effects of copper addition on the in-situ synthesis of SiC particles in Al–Si–C–Cu system

• The effect of copper addition on in-situ SiCp in Al–Si–C alloy was investigated.
• The synthesis temperature and the size of SiCp decreases with copper addition.
• The addition of copper into Al–Si–C alloy decreases its solidus temperature.
• The hardness and relative density increases when copper is added into the alloy.

In this research work, SiC particles have been successfully in-situ synthesized in Al–Si–Cu matrix alloy utilizing a novel liquid–solid reaction method. The effect of copper addition on the synthesis of SiC in Al–Si–C–Cu system was investigated. The composites mainly contain spherical SiC particles and θ-Al2Cu eutectic phases, which are embedded in the α-Al matrix. Results indicated that the temperature for forming in-situ SiC particles significantly reduced from 750 °C to 700 °C with the copper addition. The size of in-situ synthesized SiC particles can be as low as 0.2 μm. Further study found that the addition of 10 wt.% copper into Al–Si–C alloy causes its solidus temperature to decrease by about 65 °C. Additionally, the Rockwell hardness value of SiCp/Al–18Si–5Cu composites has an average of 92, which is 50% higher than that of the sample without copper addition.