SiC_P/Al-Si复合材料颗粒偏析问题及力学性能

Particle Agglomeration and Mechanical Properties of SiC_p/Al-Si Composites

采用扫描电镜对基体中Si含量和冷却速度对SiCP/Al-Si复合材料颗粒偏析问题及Si含量和冷却速度对复合材料力学性能的影响进行了研究。结果表明,当基体分别为Al-7Si、Al-12Si和Al-21Si合金时,随着基体中Si含量的增加,SiC颗粒偏析得到明显改善,但当基体中Si含量大于12%时,随着Si含量的增加,SiC颗粒偏析改善的程度不明显。当基体为Al-7Si合金时,采用砂型时,SiC颗粒被排斥到共晶体内,形成颗粒偏析;采用石墨型时,由于冷却速度快,SiC颗粒没有充分的时间做长距离的移动,SiC颗粒分布均匀。随着基体中Si含量的增加,3种基体复合材料的力学性能逐渐降低。增大冷却速度可以明显提高材料的力学性能。

Effects of different Si content and cooling rate on particle agglomeration and mechanical properties of SiCp/Al-Si composites were investigated by SEM (scanning electron microscope). The results reveal that when Si content in matrix alloy is less than 12%, with increasing in Si content, SiC particle agglomeration in the composites can be distinctly relieved, however, when Si content in matrix alloy is more than 12%, with increasing in Si content, its relief can be neglected. SiC particle in Al-7Si alloy is repelled into eutectoid to cause particle agglomeration in sand casting while it is uniformly distributed in the microstructure in graphite mold casting since high cooling rate restricts the movement of SiC particle. Mechanical properties of the composites are decreased with increasing in Si content in matrix alloy, however, it can be greatly improved with increasing in cooling rate.