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.

SiCp/Al-Si composites with different CeO2 contents were prepared by a powder metallurgy method. The effect of CeO2 content on mechanical properties, friction and wear properties of the composites was studied. The results show that with the increase in CeO2 content from 0 to 1.8 wt%, the density, hardness, friction coefficient of the composites first increases and then decreases, the coefficient of thermal expansion (CTE) and wear rate of the composites first decreases and then increases. When the content of CeO2 was 0.6 wt%, the density and hardness of the composite reached the maximum value of 98.54% and 113.7 HBW, respectively, the CTE of the composite reached the minimum value of 11.1 × 10−6 K−1, the friction coefficient and wear rate of the composite reached the maximum value of 0.32 and the minimum value of 1.02 mg/m, respectively. CeO2 has little effect on the wear mechanism of composites, and the wear mechanism of composites with different CeO2 content is mainly abrasive wear under the load of 550 N. Compared with the content of CeO2, load has a great influence on the wear properties of the composites. The wear mechanism of the composites is mainly oxidation wear and abrasive wear under low load. With the increase in load, the wear degree of abrasive particles is aggravated, and adhesive wear occurs under higher load.

Steel materials are inevitably corroded by the atmosphere, impurities or liquids, when they are widely applied to machinery, oil pipelines and so on [1][2][3][4] . One study found that the fatigue life of steel wire was decreased by about 99% if there was a tiny corrosion pit with a size of 0.2-0.6 mm, accompanied by an extremely serious damage consequence [5] . Therefore, ways to improve the corrosion resistance of steel materials at the minimum cost has been of concern. An important way to improve corrosion resistance is to avoid chemical reactions between the steel materials and the medium, especially to prevent Fe from forming galvanic cells with other elements in the steel [6][7][8][9][10] .Some corrosion-resistant elements were added during melting to change the structure of the steel materials