Preparation of CaB6-Reinforced Al/Al-Si Composites and Study of the Comprehensive Properties

In this paper, Al-CaB6 alloys were prepared by in situ melt reaction. The CaB6 particles through in situ growth are cubic with a regular shape, evenly distributed in the Al matrix. By edge-to-edge matching model's calculation, mismatch between CaB6 particles and alpha-Al was similar to 2.34%, which is less than 6%, so CaB6 can serve as the core of alpha-Al nucleation. When the amount of CaB6 addition reaches 6 wt.%, hardness of the Al-CaB6 alloy reached 34.4 HV. Besides, CaB6-particle reinforced hypereutectic Al-Si composites were prepared, and the positive influence of CaB6 particles on microstructure and properties of hypereutectic Al-Si composites was studied. The CaB6 particles show significant effect on the modification of primary silicon. Owing to the addition of CaB6 particles, the hardness of hypereutectic Al-Si alloys increased and the hardness of Al-18Si-CaB6 reached 95.1 HV. The electrochemical test of the manufactured composites revealed that the corrosion resistance of Al-18Si-CaB6 composites improved as the amount of CaB6 particle content increased. This work serves as a reference for the investigation of Al and Al-Si composites reinforced with ceramic particles.