Si在熔渗制备B4C-Si复合材料界面作用机制的第一性原理研究

First Principle Study on Interfacial Action Mechanism of Si in B4C-Si Composite Prepared by Melting and Infiltration

采用第一性原理的方法对熔渗制备B4C-Si复合材料的界面进行了研究,通过建立Si原子在B4C晶体(0001)表面的不同占位情况,获得了Si在熔渗制备B4C-Si复合材料界面的作用机制。结果表明,在熔渗温度下,孤立的Si原子更容易落在B4C晶体中二十面体形成的正六边形中心的上方,而不容易置换“C-B-C”三原子链里的C原子以形成Si C。Si原子在B4C晶体(0001)表面所处的位置是Si原子与表面C原子和周围B原子的综合作用,Si原子与C原子形成了离子键。上述结果为随后降温过程中Si原子集团与B4C晶体的结合提供了更好的晶格匹配,使得Si更容易在界面处结合。

The interface of B4C-Si composite was studied by the first-principle method, and the mechanism of Si on the interface of B4C-Si composites was obtained by establishing different occupations of Si atoms on the (0001) surface of B4C crystal. The results show that the isolated Si atoms are more likely to fall above the center of the regular hexagon formed by icosahedron in B4C crystal at the melting percolation temperature than to replace the C atoms in the three-atom chain of “C-B-C” to form SiC. The position of Si atom on the (0001) surface of B4C crystal is the combined results of Si atom with surface C atom and surrounding B atom. Si atoms form an ionic bond with C atoms. This provides better lattice matching for the combination of Si atomic group and B4C crystal in the subsequent cooling process, and makes it easier for Si to combine at the interface.