Abstract
Si-modified aluminide coatings were oxidised in air and an air + water vapour atmosphere at 1050 °C. The relationship between grain size and interdiffusion behaviour was established as a function of Al depletion in the aluminide coatings. The grain size of the aluminide coatings was characterised by electron back-scattered diffraction to account for the evolution of the grain morphology with Al content reduction during oxidation. The grain growth in the aluminide coatings was accelerated by the water-vapour-filled atmosphere, and severe internal oxidation occurred. High Al depletion led to grain growth of aluminide coating in the air + water vapour atmosphere. Ti-rich particles containing silicon were observed in the aluminide coatings, and these particles were prone to formation of interior void. In the process, these voids were associated with the Kirkendall effect.
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