Reducing the self-healing temperature of Ti2AlC MAX phase coating by substituting Al with Sn

Abstract

In an effort to overcome the property degradation of Ti2AlC MAX phase coating used in harsh environments, we fabricated a solid solution Ti2(Al0.6Sn0.4)C coating with amount of Ti5Sn3 (20 wt.%) by a combined technique composing of magnetron sputtering and post-heat treatment. The cracks induced by Vickers indentation on coating surface were self-healed at 700 ℃, which is the lowest self-healing temperature among the Al-based MAX phase coatings till now. The structural evolution and kinetic diffusion revealed that the formation of SnO2 is the key factor to achieve the crack self-healing at such a low temperature for Al-based MAX phase coatings. Additionally, the self-healed Ti2(Al0.6Sn0.4)C coating exhibited better oxidation resistance compared to the unhealed one at 800 ℃. The results provide a novel and facile strategy to develop the protective MAX phase coatings with high performance at high temperature by partially substituting Al with Sn.