EELS and STEM analysis of metal nitride/substrate interfaces

Nitride based protective coatings produced by physical vapour deposition offer a promising means to extend the oxidation and wear performance of γ-TiAl. Metal ion pre-etching of the substrate surface has been shown to significantly enhance the adhesion between the coating and substrate. In this study we have applied spectroscopic imaging and advanced STEM analysis to study such interfaces. For a conventional Cr cathodic arc discharge Cr ion implantation of ~6nm into the substrate was observed. For an etch using high power impulse magnetron sputtering the metal ion implantation depth was reduced to ~2-3nm. In both cases a corresponding depletion zone of Ti and Al was observed. In addition, nitrogen diffusion into the substrate during coating deposition was also revealed to a similar depth respectively.