层状梯度SiC/Al-Si-Mg复合材料的微观结构

以定向冷冻铸造结合挤压浸渗工艺,成功制备了SiC含量为20%的层状梯度SiC/Al-Si-Mg复合材料,采用扫描电镜(SEM)、能谱分析(EDS)以及X射线衍射(XRD),研究了复合材料的微观结构、元素分布以及SiC/Al-Si-Mg复合材料的界面。结果表明,SiC/Al-Si-Mg复合材料浸渗完全,界面结合良好,其微观结构保留了SiC陶瓷预制体中的层状梯度结构,定向梯度孔隙有利于熔体的浸渗;经1 300℃烧结处理后,预制体孔隙中SiC表面生成了SiO2,并在浸渗过程中反应生成了MgAl2O4相,从而有助于基体相和增强相之间的润湿性及界面结合强度的提高。

Microstructure of Lamellar-interpenetrated Gradient SiC/Al-Si-Mg Composites

The lamellar-interpenetrated gradient SiC/Al-Si-Mg composites with 20%SiC content(in volume fraction)were prepared by directional freeze casting combined with squeeze infiltration process.The microstructure and element distribution in composites,interface between Al-Si-Mg and SiC were investigated by scanning electron microscope(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The results reveal that liquid Al-Si-Mg alloy is completely infiltrated in the lamellar SiC preform prepared by directional freeze casting process and the interface of Al-Si-Mg and SiC in composite is well bonded.The gradient lamellar structure of SiC preform is well preserved in the composites.The SiO2 film is generated on the surface of SiC particles after sintering at 1 300℃,and the MgAl2O4 phase is formed in the infiltration process,which improves the wettability and interface bonding between the matrix phase and the reinforced phase.