CDS铸造过共晶铝硅合金组织及性能研究

Study on Microstructure and Property of Hypereutectic Al-Si Alloy by CDS Casting

采用受控扩散凝固（CDS）技术制备Al—20％Si合金，研究了混合方式和高硅合金的混合温度对目标合金组织和性能的影响，探讨了合金组织与热膨胀性能之间的关系。结果表明，采用受控扩散凝固技术，纯铝液（660℃）与高硅合金液（850℃）混合所制备的目标合金初生硅相分布均匀，形貌规整，尺寸最小，合金的线膨胀系数也最小（15．7×10^-6℃^-1，30-300℃）。分析表明，Al—20％Si合金热膨胀性能主要取决于合金组织中初生相的分布和形貌的规整性，与尺寸大小关系不大。

By using the controlled diffusion solidification （CDS） technology, the hypereutectic A1-20%Si alloy was prepared. The effects of mixing ways and mixing temperature of high-silicon alloy on microstructure and properties of target alloy as well as the relationship between microstructure and thermal expansion property have been studied. The results show that the target alloy prepared by CDS process, namely mixing liquid pure-Al （660 ℃ ） with liquid Al-25% Si （850 ℃ ） alloy, has the lowest linear expansion coefficient （15.7×10^-6℃^-1 from30-300℃ to 300 ℃ ） , the primary silicon phase of the alloy distributes uniformly, its shape is regular and size is minimal. The analysis shows that thermal expansion property of Al-20%Si alloy is mainly depends on the morphology and distribution of primary silicon, which has little relation to the grain size.