Two types of MCrAlY coatings NiCoCrAlY and NiCoCrAlYHfSi were deposited on DD6 specimens by electron beam physical vapor deposition (EB-PVD) and low pressure plasma spray (LPPS) respectively. The coating surface

cross-section morphologies and phase structures of the specimens were investigated by scanning electron microscopy (SEM)

energy dispersive spectroscopy (EDS)

electron probe micro-analyzer (EPMA) and X ray diffraction (XRD) after 1100℃ cyclic oxidation for different time. The utilization of NiCoCrAlY and NiCoCrAlYHfSi coatings prominently enhance the oxidation resistance of DD6 alloy. After 100h oxidation

α-Al2O3 is still the major phase in the oxide scales formed on the coated specimens. Inter-diffusion occurs between the coatings and the substrate

which leads to the formation of the interdifusion zone (IDZ) and second reaction zone (SRZ). The rod-like TCP phase and the granular TCP phases precipitated in the SRZ

which are rich in W

Re

Mo. Reactive elements (RE) Si

Hf have suppression action on the formation of Cr-rich phase and the growth rate of TGO.