TThe physical characteristics and volume growth of TGOs in TBC systems lead to TBC failure. It is proved that enriching the BC/TC interface with α-Al2O3 is beneficial to an extended operational time by prolonging the steady-state growth stage of the TGO. The corresponding phase reactions in TBC systems with heightened Al activity, however, are not studied yet. In this work, the stage formation of TGO layers of TBC systems with PVD-Al interlayers is described. The study uses thermal cyclic loading with dwell time at maximum high temperature of 1,150 °C. The crack formation in the ceramic top coat and the TGOs thickness at the interface are investigated by SEM/EDS after 1, 6, 12, 24, 40 and 80 thermal cycles. The results plot the interface change and crack formation as a function of the thermal cycle number. The corresponding failure mode is discussed.

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