Interfacial Reaction of Super α_2 and Ti_2AlNb Composites Reinforced by SCS-6 SiC Fibers

摘要

Interfacial reactions of SCS-6 SiC fiber reinforced super α_2 and Ti_2AlNb matrix composites were investigated, respectively, by means of analytical transmission electron microscopy and by thermodynamics. Up to six interfacial reaction layers, TiC and Ti_5Si_3 with fine grains, equiaxed TiC, Ti_3Si, Ti_3AlC and elongated grains of Ti_5Si_3, distribute from fiber side to matrix side in thermally exposed SCS-6 SiC/super α_2 composite. However, in SCS-6 SiC/Ti_2AlNb composites thermally exposed, the interfacial reaction zone consists of four layers of fine grained TiC and Ti_5Si_3, equiaxed TiC and Ti_3Si, in addition to Ti_3AlC particles inside the Ti_2AlNb matrix apart from interface. The reaction zone is much thicker in SCS-6 SiC/super α_2 than in SCS-6 SiC/Ti_2AlNb. It is found that the predicted variation of the strength of SCS-6 SiC/super α_2 with its thickness of interfacial reaction zone accords with the experimental one. Thermodynamic study on the interfacial reaction was conducted based on quantum chemistry calculation. The interfacial reaction mechanism was discussed.