Wetting and interfacial behavior of Al-Ti/4H-SiC system:A combined study of experiment and DFT simulation

Wetting and interfacial behavior of molten Al-(10, 20, 30, 40) at.%Ti alloys on C-terminated 4H-SiC at 1500 and 1550 degrees C were investigated experimentally, and theoretical bonding strength, structure stability and electronic structure of interfacial reaction products/C-terminated 4H-SiC interfaces were evaluated by first-principle calculations. The wetting experiments show that the Al-Ti/SiC systems present excellent wettability with contact angle of less than 15 degrees except the Al-40Ti/SiC system performed at 1500 degrees C x 30 min. The SEM-EDS and TEM analyses demonstrate that the reaction products are mainly composed of Al4C3, TiC, Ti3SiC2, Ti5Si3CX and tau phase, and their formation and evolution can be mainly affected by the Ti concentration in the Al-Ti alloys and wetting temperature. Moreover, the calculated results show that the SiC/C-terminated TiC interface presents the highest work of separation and its electronic property reveals that the localization of electrons and formation of covalent bond between interfacial C atoms lead to the excellent bonding strength of SiC/TiC interface.