SiCp/AZ91D magnesium matrix composites with 30% SiCp were successfully prepared by pulsed current melting in this work. Then, the influences of the pulse current on the microstructure, phase composition, and heterogeneous nucleation of the experimental materials were analyzed in detail. The results show that the grain size of both the solidification matrix structure and SiC reinforcement are refined by pulse current treatment, and the refining effect is gradually more obvious with an increase in the pulse current peak value. Moreover, the pulse current reduces the chemical potential of the reaction between SiCp and Mg matrix, thus promoting the reaction between SiCp and the alloy melt and stimulating the formation of Al4C3 along the grain boundaries. Furthermore, Al4C3 and MgO, as heterogeneous nucleation substrates, can induce heterogeneous nucleation and refine the solidification matrix structure. Finally, when increasing the peak value of the pulse current, the repulsive force between the particles increases while the agglomeration phenomenon is suppressed, which results in the dispersed distribution of SiC reinforcements.

中文翻译：

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脉冲电流作用下SiCp/AZ91镁基复合材料异相形核机制研究。

在这项工作中，通过脉冲电流熔化成功地制备了具有 30% SiCp 的 SiCp/AZ91D 镁基复合材料。然后，详细分析了脉冲电流对实验材料的微观结构、物相组成和异相形核的影响。结果表明，脉冲电流处理细化了凝固基体组织和SiC增强体的晶粒尺寸，且细化效果随着脉冲电流峰值的增大而逐渐明显。此外，脉冲电流降低了SiCp与Mg基体反应的化学势，从而促进了SiCp与合金熔体的反应，刺激了Al4C3沿晶界的形成。此外，Al4C3 和 MgO 作为异质成核基底，可以诱导异质形核并细化凝固基体结构。最后，当增加脉冲电流的峰值时，颗粒间的排斥力增加，团聚现象受到抑制，导致SiC增强体分散分布。