Thermal cycling behavior and stress distribution in TGO layer of MCrAlYX-type coatings via high-current pulsed electron beam modification

Abstract

In this contribution, NiCoCrAlYSiHf coatings were modified via high-current pulsed electron beam (HCPEB) technique. The surface states (roughness and residual stress) and the microstructures (phase compositions, crystal defects and reactive element distribution) were characterized and analyzed. The coatings were subjected to the thermal cycling test at 1100 °C. The high-temperature service performance of the coatings was evaluated by comparing the oxidation kinetic behavior and the cross-sectional morphologies of the thermally grown oxide (TGO). The stress was measured according to the real TGO morphology after different thermal cycles as a reference for evaluating the thermal cycling oxidation resistance. The experimental results demonstrate that the irradiated coatings achieved a flat remelted surface with rich microscopic plastic deformation and uniformly distributed Y-rich precipitates. These properties ensure the thermostability of the TGO during thermal cycling, hence significantly alleviating the TGO spallation. The modified coating has shown a superior thermal cycling behavior.