Early stages of oxidation of Ti3AlC2 ceramics

Abstract

Abstract The nucleation and growth of oxide scale at the early stages of oxidation of Ti3AlC2 ceramics was studied via oxidizing at 1100 °C in air for short times (≤900 s). The nucleation of nanosized Al2O3 particles mainly occurs at the ledges of the fractured lamellar Ti3AlC2 grains as well as on the {0 0 0 1} basal surfaces. The Al2O3 nuclei mainly grow along these ledges to form oxide strings, and then spread on the terraces and the {0 0 0 1} basal surfaces. An oxide layer consisting predominantly of nanosized α-Al2O3 forms after oxidizing for 180 s. The formation of lenticular hexagonal pores in Ti3AlC2 grains is attributed to the faster consumption of Ti, Al and C atoms along 〈 1 1 2 ¯ 0 〉 direction than along 〈0 0 0 1〉 direction. With further oxidation, rutile-TiO2 particles form on top of the α-Al2O3 layer, and grow to form a rutile-TiO2 layer. Further oxidation leads to the formation of pores underneath the primary α-Al2O3 layer. In this porous layer both Al2O3 and TiO2 were present with a preference for Al2O3 to stay adjacent to the inward moving interface of Ti3AlC2 substrate.