Kinetics and mechanism of interfacial reaction in SCS-6 SiC continuous fiber-reinforced Ti-Al intermetallic matrix composites

SCS-6 SiC continuous fiber-reinforced Ti-Al intermetallics-matrix composites were fabricated by HIP method and then heat-treated in vacuum under different conditions. The interfacial reaction kinetics and mechanism were studied by using SEM, EDS and XRD. The results show that the content fluctuation of reactive elements such as C, Ti and Si appears in interfacial reaction layers, and multi-layer interfacial reaction compounds form. Alloying element Nb in matrix remarkably diffuses into interfacial reaction zone and changes the activation energy for the interfacial reaction layer growth following a role of parabolic rate. The activation energy (Qk) and (k0) of SCS-6 SiC/super α2 and SCS-6 SiC/Ti2AlNb are 317.664 kJ/mol, 175.709 kJ/mol and 5.4438×10-2 m/s1/2, 1.44×10-5 m/s1/2; respectively, and the diffusion coefficient (DC) is about 10-18—10-20 m2/s. It is confirmed that the SCS-6 SiC/Ti-Al intermetallic composites have higher interface compatibility and stability. Furthermore, compared with SCS-6 SiC/super α2, the interface compatibility and stability of SCS-6 SiC/Ti2AlNb are even higher.

SCS-6 SiC continuous fiber-reinforced Ti-Al intermetallics-matrix composites were fabricated by HIP method and then heat-treated in vacuum under different conditions. The interfacial reaction kinetics and mechanism were studied by using SEM, EDS and XRD. The results show that the content fluctuation of reactive elements such as C, Ti and Si appears in interfacial reaction layers, and multi-layer interfacial reaction compounds form. Alloying element Nb in matrix remarkably diffuses into interfacial reaction zone and changes the activation energy for the interfacial reaction layer growth following a role of parabolic rate. The activation energy （Qk） and （k0） of SCS-6 SiC/super α2 and SCS-6 SiC/Ti2AlNb are 317.664 kJ/mol, 175.709 kJ/mol and 5.4438X 10^-2m/s^1/2, 1.44× 10^-5 m/s^1/2; respectively, and the diffusion coefficient （Dc） is about 10^-18--10^-20 m^2/s. It is confirmed that the SCS-6 SiC/Ti-Al intermetallic composites have higher interface compatibility and stability. Furthermore, compared with SCS-6 SiC/super α2, the interface compatibility and stability of SCS-6 SiC/Ti2AINb are even higher.