Effects of High Temperature Oxidation on Mechanical Properties of Ti3AlC2

The oxidation tests of Ti3AlC2 were conducted at 1100 and 1200 °C in air for 48 and 360 h, respectively, and the effects of high temperature oxidation on the flexural strength and hardness of Ti3AlC2 were investigated. The microstructure, grain size and phase compositions of Ti3AlC2 substrate didn't change after oxidation, hence the oxide removed Ti3AlC2 substrate maintained its initial flexural strength and hardness. However, the flexural strength of oxide retained Ti3AlC2 decreased by about 5%. Acoustic emission monitoring indicated that during the process of three-point bending test, the formed Al2O3 scale on Ti3AlC2 surface fractured firstly in a cleavage manner, then the substrate/oxide interface cracked, and finally the Ti3AlC2 substrate fractured. The mechanical degradation was caused by the preferential formation of cracks in brittle Al2O3 scale as well as at defective and lacunose grain boundaries of the substrate where stress concentration generated. The mechanical degradation was insensitive to oxidation temperature and time in the present conditions. In addition, the surface hardness increased significantly after oxidation due to the formed hard Al2O3 scale on the surface of Ti3AlC2 substrate.