In situ aluminum matrix composites were fabricated by the addition of a gelated BS290 silicone polymer precursor to molten aluminum where the polymer gel was pyrolyzed in the melt and produced ceramic phases with chemical composition close to that of SiOC. The results indicated successful incorporation of in situ formed micro-sized particles in the melt, which acted as reinforcement and nucleation sites in the aluminum matrix. Homogeneous dispersion of the in situ formed particles in the matrix was attributed to rapid release of a large amount of gas during pyrolysis, which would disintegrate the particles’ agglomerates. The fabricated composites had mostly equiaxed and much finer grains than their corresponding monolithic cast sample. To improve SiOC particles’ distribution and to remove the structural porosity, both composite and monolithic samples were hot extruded at 400 °C. Hardness, yield strength and compressive strength of the extruded composite sample were found to be about 23, 53 and 18% higher than those of the extruded monolithic sample, respectively. Fractography of the fracture surface of the tensile test samples indicated a ductile fracture mode for both extruded samples. Elastic modulus mismatch was recognized as the main strengthening mechanism for the composite sample.

Graphic abstract

中文翻译：

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硅聚合物凝胶在铝熔体中原位热解制备的原位Al-SiOC复合材料

原位铝基复合材料是通过将凝胶化的 BS290 有机硅聚合物前体添加到熔融铝中来制造的，其中聚合物凝胶在熔体中热解并产生化学成分接近 SiOC 的陶瓷相。结果表明成功地在熔体中原位形成了微尺寸颗粒，这些颗粒在铝基体中起到了增强和成核点的作用。原位形成的颗粒在基体中的均匀分散归因于热解过程中大量气体的快速释放，这会分解颗粒的团块。与相应的整体铸造样品相比，制造的复合材料大多具有等轴和更细的晶粒。为了改善SiOC颗粒的分布并去除结构孔隙，复合材料和整体样品均在 400 °C 下热挤压。发现挤压复合样品的硬度、屈服强度和压缩强度分别比挤压整体样品高约 23%、53% 和 18%。拉伸试样断裂面的断口分析表明两种挤压试样均具有延展性断裂模式。弹性模量失配被认为是复合材料样品的主要强化机制。

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