基于第一性原理的Si/SiC、Al/SiC界面成键特性和结合强度对比研究

采用半固态搅拌铸造法制备Al Si7-Si C复合材料，并利用真空压铸工艺实现了其近净成形，结合第一性原理计算方法研究了共晶Si对Si C颗粒和基体界面结合强度的影响.结果显示，在Al Si7-Si C复合材料中，发现较为严重的共晶Si偏析现象，当Si C颗粒同时处于共晶Si和α-Al边界时，形成了少量的共晶Si夹杂、被大量共晶Si包裹、完全被共晶Si包裹三种典型的界面.第一性原理计算结果显示，在C端和Si端的Si/Si C界面中，弛豫后top Si¹配位方式具有最大的粘附功，与Al/Si C界面相比，Si/Si C界面具有更高的结合强度.Si偏析相提高了界面处的电荷密度，因而具有更好的界面结构稳定性.

Comparative Study on Bonding Characteristics and Bonding Strengths of Si/SiC and Al/SiC Interfaces Based on First principles

AlSi7-SiC composite was prepared by semi-solid stirring casting, and its near-net shape forming was achieved by vacuum die casting. The influence of eutectic Si segregation on the interface strength of SiC-Al composite was studied by the first principles calculation method. The results shown that a mass of eutectic Si segregation was found in the matrix of the prepared AlSi7-SiC composites and three typical interfaces were formed: mixed up with a few eutectic Si, a half trapped in eutectic Si and completely trapped in eutectic Si. The calculation results shown that the Si/SiC interface with C-terminated and Si-terminated, the topSi1 coordination mode has the largest adhesion work after relaxation. The interface bonding strength of the Si/SiC interface is greater than that of the Al/SiC interface. Compared with the Al/SiC interface, the Si/SiC interface had a better stability of interface structure attributed to the strong covalent bond formed at the Si/SiC interface and the segregated Si phase improved the interfacial charge density.