The iron effect on oxidation and interdiffusion behaviour in MCrAlX coated Ni-base superalloys [Elektronisk resurs]

• Two MCrAlX powders with different Fe content were deposited on an IN792 superalloy using high velocity oxygen-fuel spraying (HVOF). The oxidation and interdiffusion behaviour of the coated specimens were investigated at 900, 1000 and 1100 degrees C for different exposure times. Experimental results showed that high Fe addition in the MCrAlX coating had no obvious effect on oxidation, however, a great impact on coating-substrate interdiffusion and coating degradation was observed. Although no influence on Al diffusivity in IN792, high Fe addition promotes the formation of a discontinuous sigma phase layer at the coating/substrate interface, which retards Al diffusion in the IN792 substrate at 900 degrees C. To investigate Fe influence on phase equilibrium, thermodynamic calculation was also performed. It was shown that high Fe addition in the MCrAlX coating increased the beta phase fraction and stabilized the beta phase by extending the beta + gamma phase region. Besides, high Fe addition in the MCrAlX coating modifies Cr diffusion, and alters local phase equilibrium at the coating/substrate interface. These two factors suppress inner-beta depletion of high Fe containing coating. Grain coarsening of the coating can be observed during oxidation, it was retarded by high Fe addition. (C) 2019 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license 

Ämnesord

Engineering and Technology  (hsv)

Materials Engineering  (hsv)

Manufacturing, Surface and Joining Technology  (hsv)

Teknik och teknologier  (hsv)

Materialteknik  (hsv)

Bearbetnings-, yt- och fogningsteknik  (hsv)

Genre

government publication  (marcgt)

Indexterm och SAB-rubrik

Coating; Iron addition; Interdiffusion; Thermodynamics; Microstructure