Effect of Ti and Ta on Oxidation Kinetic of Chromia Forming Ni-Base Superalloys in Ar-Osub2/sub-Based Atmosphere

摘要

In the present study, two commercially available Ni-base superalloys, namely Rene 80 which contains Ti and IN 792 containing Ti and Ta, were investigated during isothermal oxidation at 1,050°C in Ar–20 O_(2) gas up to 50 h. It was found that IN 792 showed a slightly lower oxidation rate as compared to Rene 80. Also differences in oxide scale microstructures and thicknesses were found. Both alloys formed qualitatively similar oxide scales consisting of outer TiO_(2) on top of a Cr_(2)O_(3) scale and internally oxidized Al_(2)O_(3). The IN 792 formed a thinner oxide scale in general as well as a thinner outer TiO_(2) scale. Also the depth of the internally oxidized Al_(2)O_(3) precipitates is smaller in case of IN 792. These findings were correlated with the formation of TiTaO_(4), which in turn hampered outer Ti and inward oxygen flux.