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 α-Al was ~2.34%, which is less than 6%, so CaB₆ can serve as the core of α-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.