Ca含量对SiC/Al泡沫复合材料性能和结构的影响

研究了SiC颗粒增强铝基（SiC/Al）复合材料中Ca含量对SiC分散性的影响以及Ca含量对注气法制备的SiC/Al泡沫复合材料的压缩性能和结构的影响。首先，制备不同Ca含量的SiC/Al复合材料，用来制备SiC/Al泡沫复合材料的基本材料，并对不同Ca含量的SiC/Al泡沫复合材料进行压缩实验；然后，利用OM、SEM和XRD研究了SiC/Al复合材料及泡沫结构中Ca含量对SiC分散性的影响。结果表明:Ca的加入会明显影响SiC/Al复合材料中SiC的分布，且存在Ca含量临界值。当Ca含量小于1.5wt%时，SiC在基体中分布较均匀；当Ca含量达到或超过1.5wt%时，熔体中生成一种富含Al、Ca和Si的金属间化合物Ca₂Al₄Si₃，且其体积分数和尺寸随Ca含量的提高而显著增大，SiC集聚在这些金属间化合物区域内及其边界上而影响SiC分布的均匀性。压缩实验表明，SiC/Al泡沫复合材料压缩应力-应变曲线的平台应力和抗压屈服强度随着Ca含量的增加有提高的趋势。相应的SiC/Al泡沫复合材料的胞壁厚度随着Ca含量的提高明显增加，这不仅与金属间化合物的形成提高了熔体黏度相关，更可能是与金属间化合物在熔体中尺寸随Ca含量提高而明显增大相关。 

Effect of Ca content on property and structure of SiC/Al foam composites

The effects of Ca content on SiC dispersity in SiC reinforced aluminum matrix(SiC/Al) composites, and the effects of Ca content on the compressive property as well as the structure of SiC/Al foam composites prepared by gas injection method were investigated. Firstly, the SiC/Al composites with different Ca contents were prepared as base materials for the fabrication of SiC/Al foam composites, and the compressive test was conducted to the SiC/Al foam composites with different Ca contents. Then the effects of Ca content on SiC dispersity in the SiC/Al composites and foam structure were analyzed using OM, SEM and XRD. The results show that the addition of Ca can obviously affect the SiC distribution in the SiC/Al composites and there is a critical value of Ca content. SiC distributes uniformly in matrix when Ca content is smaller than 1.5wt%. Intermetallic compounds Ca₂Al₄Si₃ which are rich of Al, Ca and Si form in the melt when Ca content reaches or exceeds 1.5wt%. Their volume fraction and size increase obviously with the increasing of Ca content, which leads to the aggregation of SiC in these intermetallic compounds and their boundaries, affecting the uniformity of SiC distribution. The compressive test reveals that the plateau stress and the compressive yield strength of the compressive stress-strain curves for SiC/Al foam composites have an increasing tendency with Ca content increasing. The corresponding cell wall thickness of SiC/Al foam composites also increases obviously with the increasing of Ca content. It is not only related to the melt viscosity improved by the formation of intermetallic compounds, but more likely related to the size of intermetallic compounds in the melt increasing with the increasing of Ca content.