Abstract：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.
2017, 
