Slurry based diffusion coatings for blade under platform of internally-cooled components and process therefor

A method of coating a component, comprising:

• applying an aluminizing slurry to a localized area of a component;
• drying the aluminizing slurry;
• heat treating the aluminizing slurry;
• applying a chromizing slurry to the localized area of the component subsequent to heat treating the aluminizing slurry;
• drying the chromizing slurry;
• and
• heat treating the chromizing slurry so as to form a diffusion coating on the localized area of the component, the diffusion coating comprising an interdiffusion zone at an interface between the diffusion coating and the component, the diffusion coating further comprising a non-metallic inclusions zone adjacent to an outer surface of the diffusion coating, wherein the diffusion coating is a Cr-enriched γ-Ni based layer, and wherein the interdiffusion zone comprises elongated refractory element-rich particles, wherein Cr content and Al content are distributed through the diffusion coating such that a single diffusion coating layer contains the Cr content and the Al content.