Cyclic oxidation behaviour of the titanium alloys Ti-6242 and Ti-17 with Ti–Al–Cr–Y coatings at 600 and 700 °C in air

Oxidation protective intermetallic Ti–Al–Cr–Y coatings of 10 μm thickness were deposited on specimens of the near-α alloy Ti-6242 and the (α + β) alloy Ti-17 using magnetron sputtering. The oxidation behaviour of the coated samples was studied at 600 °C and 700 °C under cyclic oxidation conditions in air. The coatings exhibited very good adhesion to the substrate materials and provided effective oxidation protection to the titanium alloys at both temperatures. A thin alumina scale formed on top of the coatings which showed a multi-phase microstructure consisting of the Ti(Cr,Al)2 Laves phase and, dependent on exposure temperature and time, the γ-TiAl, r-TiAl2 and/or AlCr2 phases.