The CMSX 4 superalloy was coated with rhodium 0.5-μm thick layer and next aluminized by the CVD method. The coating consisted of two layers: the additive and the interdiffusion one. The outward diffusion of nickel from the substrate turned out to be a coating growth dominating factor. The additive layer consists of the β-NiAl phase, whereas the interdiffusion layer consists of the β-NiAl phase with precipitates of σ and μ phases. Rhodium has dissolved in the coating up to the same level in the matrix and in the precipitates. The oxidation test proved that the rhodium modified aluminide coating showed about twice better oxidation resistance than the nonmodified one.
Keywords: CMSX 4 superalloy; TEM analysis; rhodium.
© 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.