Reaction diffusion in continuous SiC fiber reinforced Ti matrix composite

摘要

SiC continuous fiber-reinforced pure Ti(TAl) matrix composites were fabricated by a vacuum hot pressing(VHP) method and then heat-treated in vacuum under different conditions. The interfacial reaction and the formation of interfacial phases were studied by using SEM, EDS and XRD. The results show that there exists reaction diffusion at the interface of SiC fibers and Ti matrix, and the concentration fluctuation of reaction elements such as C, Ti and Si appears in interfacial reaction layer. The interfacial reaction products are identified as Ti_3SiC_2, TiC_x and Ti_5Si_3C_x. At the beginning of interfacial reaction, the interfacial reaction products are TiC_x and Ti_5Si_3C_x. Along with the interfacial reaction diffusion, Ti_3SiC_2 and Ti_5Si_3C_x single-phase zones come forth in turn adjacent to SiC fibers, and the TiC+Ti_5Si_3C_x double-phase zone appears adjacent to Ti matrix, which forms discontinuous concentric rings by turns around the fibers. The formed interfacial phases are to be Ti_3SiC_2, Ti_5Si_3C_x and TiC_x+Ti_5Si_3C_x from SiC fiber to Ti matrix. The interfacial reaction layer growth is controlled by diffusion and follows a role of parabolic rate, and the activation energy (Q~k) and (k_0) of SiC/TA1 are 252.163 kJ/mol and 7.34 x 10~(-3) m/s~(1/2), respectively.