High temperature oxidation of Ti-46Al-6Nb-0.5W-0.5Cr-0.3Si-0.1C alloy

A newly developed Ti-46Al-6Nb-0.5W-0.5Cr-0.3Si-0.1C alloy was oxidized isothermally and cyclically in air, and its high-temperature oxidation behavior was investigated. When the alloy was isothermally oxidized at 700 degrees C for 2000 h, the weight gain was only 0.15 mg/cm(2). The parabolic rate constant, k(p) (mg(2)/cm(4).h), measured from isothermal oxidation tests was 0.002 at 900 degrees C and 0.009 at 1000 degrees C. Such excellent isothermal oxidation resistance resulted from the formation of the dense, continuous Al2O3 layer between the outer TiO2 layer and the inner (TiO2-rich, Al2O3-deficient) layer. The alloy also displayed good cyclic oxidation resistance at 900 degrees C. Some noticeable scale spallation began to occur after 68 h at 1000 degrees C during the cyclic oxidation test. (C) 2016 Elsevier Ltd. All rights reserved.