Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

► Sputtered NiAl-Cr-Hf as overlay coatings. ► Annealing triggered interdiffusion and precipitation. ► Precipitates formed within coating and along grain boundaries. ► Hf segregation to coating surface inhibited when added with Cr. ► Hf solubility increased in Cr-containing alloy.