MAX phase formation by intercalation upon annealing of TiC_x/Al (0.4≤x≤1) bilayer thin films

TiC_x/Al bilayer thin films were synthesized using combinatorial magnetron sputtering to study the influence of C content on the reaction products at different annealing temperatures. Based on energy dispersive X-ray analysis calibrated by elastic recoil detection analysis data, x in TiC_x was varied from 0.4 to 1.0. Film constitution was studied by X-ray diffraction before and after annealing at temperatures from 500 to 1000°C. The formation of TiC_x and Al in the as-deposited samples over the whole C/Ti range was identified. Upon annealing TiC_x reacts with Al to form the Ti-Al based intermetallics. Already at 700°C, the formation of MAX phases (space group P63/mmc) is observed at x≤0.7. Based on the comparison between the C content induced changes in the lattice spacing of TiC_x and Ti₂AlC as well as Ti₃AlC₂, we infer the direct formation of MAX phases by Al intercalation into TiC_x for x≤0.7.