Preparation of Ti2AlC MAX Phase Coating by DC Magnetron Sputtering Deposition and Vacuum Heat Treatment

Due to the excellent corrosion resistance and high irradiation damage resistance, Ti2AlC MAX phase is considered as a candidate for applications as corrosion resistant and irradiation resistant protective coating. MAX phase coatings can be fabricated through firstly depositing a coating containing the three elements M, A, and X close to stoichiometry of the MAX phases using physical vapor deposition, followed by heat treatment in vacuum. In this work, Ti-Al-C coating was prepared on austenitic stainless steels by reactive DC magnetron sputtering with a compound Ti50Al50 target, and CH4 used as the reactive gas. It was found that the as-deposited coating is mainly composed of Ti3AlC antiperovskite phase with supersaturated solid solution of Al. Additionally, the ratio of Ti/Al remained the same as that of the target composition. Nevertheless, a thicker thermally grown Ti2AlC MAX phase coating was obtained after being annealed at 800 °C in vacuum for 1 h. Meanwhile, the ratio of Ti/Al became close to stoichiometry of Ti2AlC MAX phases. It can be understood that owing to the higher activity of Al, it diffused quickly into the substrate during annealing, and then more stable Ti2AlC MAX phases transformed from the Ti3AlC antiperovskite phase.