Crystallographic and TEM Features of a TBC/Ti2AlC MAX Phase Interface after 1300 °C Burner Rig Oxidation

A FIB/STEM interfacial study was performed on a TBC/Ti2AlC MAX phase system, oxidized in an aggressive burner rig test (Mach 0.3 at 1300 °C for 500 h). The 7YSZ TBC, α-Al2O3 TGO, and MAXthal 211TM Ti2AlC base were variously characterized by TEM/STEM, EDS, SADP, HRTEM. YSZ mix of “clean” featureless “faulted” high contrast grains. latter exhibited ferro-elastic domains Y content tetragonal t″ variants. No martensite observed. TGO essentially duplex structure inner columnar plus outer equiaxed It maintained perfectly intact, clean interface with the substrate. substrate no Al-depletion zone but, rather, numerous faults along basal plane hexagonal structure. These are believed to offer means depleting Al forming crystallographic, low-Al planar defects, proposed as Ti2.5AlC1.5. characterizations support augment prior optical, SEM, XRD findings that demonstrated remarkable durability YSZ/Ti2AlC system tests.