Structural stability and oxidation resistance of amorphous TaSi-based ternary alloy coatings

Abstract

Amorphous metal coatings have great potential for corrosion protection but finding alloy compositions which form a stable amorphous structure can be an overwhelming task. We use combinatorial magnetron sputtering and X-ray analysis to map out the phase space of TaSiM (M = Al, Cr, Fe, Ti) alloys in order to identify amorphous compositions. Atomic percentages of above 10–15 at.% of each constituent yield amorphous coatings in all four systems. TaSiAl coatings are stable when annealed in air up to and including 550 °C whereas TaSiFe, TaSiCr and TaSiTi remain amorphous up to and including 750 °C. In particular, Ta₃₅Si₁₅Cr₅₀ is almost unchanged at that temperature, and has a stable surface oxide shell less than 20 nm in thickness at 650 °C. The stability of these materials at high temperatures means that they could be suitable as anti-corrosion coatings in high temperature applications.