Synthesis of Hf-modified aluminide coatings on Co-base superalloys

Hf-modified and Hf–Pt-modified aluminide coatings on Haynes 188 Co-base alloy coupons were developed and furthermore, Hf-modified aluminide coatings on MAR-M-509 Co-base aircraft turbine engine vane segments were produced for potential industrial applications. Surface morphology and cross-section microstructure of the developed coatings were inspected and compared by using Scanning Electron Microscope (SEM) equipped with energy dispersive spectroscopy (EDS), and Glow-Discharge Mass Spectrometry (GDMS). Experimental results showed that Hf was successfully incorporated and localized Hf-rich precipitated phase particles were observed on the coating surface and within the coating additive layer. The Hf-rich particles and the effect of heat treatment on the particles are also discussed.