Mechanical characterization of DC magnetron sputtered amorphous Ti–Al–Cr coatings

Recent research efforts have established that Laves phase reinforced gamma titanium aluminides (i.e. γ+Laves) offer significant potential as oxidation resistant coating in high-temperature structural applications. In this study TiAlCr coatings were d.c. magnetron sputtered from a Ti-51Al–12Cr alloy target onto silicon substrates. The microstructures, mechanical properties, and stress evolution have been investigated in as-deposited films and in films annealed in an argon atmosphere. The amorphous structure found in the as-deposited coatings was retained after thermal cycling to 500 °C. After annealing the coatings exhibited improved hardness, higher reduced modulus, and smaller CTE values, which likely result from densification of coatings induced by thermal cycling and surface oxidation.