Insights into high temperature oxidation of Al2O3-forming Ti3AlC2

Insights into high temperature oxidation of Al2O3-forming Ti3AlC2 are made to understand the sub-parabolic oxidation rate and the absence of Al-depletion zone beneath the protective Al2O3 scale. The scale results from selective oxidation of Al that migrated from Ti3AlC2 according to Ti3AlC2 + 3/2y O-2 -> Ti3Al1-yC2 + 1/2y Al2O3, leaving Al vacancy in the substrate. Inward diffusion of oxygen via grain boundaries of the Al2O3 scale predominates for the scale growth. The Al2O3 grains grow with time, yielding sub-parabolic oxidation kinetics. The Al diffuses in a fast manner, accounting for the absence of Al-depletion zone. (C) 2012 Elsevier Ltd. All rights reserved.