Long-time oxidation of Ti3AlC2 between 400 and 800 degrees C in air

Abstract

The air-oxidation behavior of bulk samples of Ti3AlC2 was investigated between 400 and 800 degrees C for 10 h similar to 12 months, with an emphasis being placed on elucidating the anomalous oxidation characteristics of Ti3AlC2 at 600 degrees C. Ti3AlC2 oxidized faster than TiAl, due to the abundance of Ti and carbon. At 800 degrees C, Ti3AlC2 oxidized to rutile-TiO2 and alpha-Al2O3. At 800 degrees C, anatase-TiO2 transformed rapidly into the more stable rutile-TiO2, and Al2O3 also formed internally along the boundaries of lamellar matrix grains underneath the oxide scale. At 600 degrees C, Ti3AlC2 oxidized to TiO2 in the form of rutile, anatase, or amorphous, plus Al2O3 in the form of crystalline, or amorphous, depending on the oxidation time. The origin of anomalous oxidation is proposed as the oxidation of Ti to TiO2, and the slow growth rate of alumina at intermediate temperatures. The formation of TiO2 resulted in a volume expansion, cracking Ti3AlC2 seriously at 600 degrees C.