Effects of CeO(2) on the Si Precipitation Mechanism of SiCp/Al-Si Composite Prepared by Powder Metallurgy

SiCp/Al-Si composites with different CeO(2) contents were prepared by a powder metallurgy method. The effect of CeO(2) content on the microstructure of the composites was studied. The mechanism of CeO(2) on the precipitation of Si during sintering was analyzed by theoretical calculations. The results show that the appropriate amount of CeO(2) can significantly refine the size of precipitated Si particles in the composite and increase the number of Si particles. With the increase of CeO(2) content from 0 to 0.6 wt%, the number of Si particles precipitated in the composites increases gradually, and the average particle size of Si particles decreases gradually. When the CeO(2) content is 0.6 wt%, the number of Si particles precipitated in the composites reaches the maximum, and the average particle size reaches the minimum. However, with the increase of CeO(2) content from 0.6 wt% to 1.8 wt%, the number of Si particles precipitated in the composites began to decrease, and the average size of Si particles gradually increased. CeO(2) can be used as heterogeneous nucleation substrate of precipitated Si, and the nucleation rate of precipitated Si on a CeO(2) substrate is higher than that on an aluminum substrate. The proper addition of CeO(2) can improve the nucleation efficiency of precipitated Si, thus increasing the amount and refining the size of precipitated Si.