Effects of CeO₂ on the Si Precipitation Mechanism of SiCp/Al-Si Composite Prepared by Powder Metallurgy

• Main Authors: Bin Yang, Aiqin Wang, Kunding Liu, Chenlu Liu, Jingpei Xie, Guangxin Wang, Shizhong Wei
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Materials
• Subjects: powder metallurgy; rare earth element; precipitated Si; microstructure refinement
• Online Access: https://www.mdpi.com/1996-1944/13/19/4365

SiCp/Al-Si composites with different CeO₂ contents were prepared by a powder metallurgy method. The effect of CeO₂ content on the microstructure of the composites was studied. The mechanism of CeO₂ on the precipitation of Si during sintering was analyzed by theoretical calculations. The results show that the appropriate amount of CeO₂ can significantly refine the size of precipitated Si particles in the composite and increase the number of Si particles. With the increase of CeO₂ 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 CeO₂ 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 CeO₂ 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. CeO₂ can be used as heterogeneous nucleation substrate of precipitated Si, and the nucleation rate of precipitated Si on a CeO₂ substrate is higher than that on an aluminum substrate. The proper addition of CeO₂ can improve the nucleation efficiency of precipitated Si, thus increasing the amount and refining the size of precipitated Si.