Effects of High Temperature Oxidation on Mechanical Properties of Ti3AlC2

The oxidation tests of TiAlCwere 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 TiAlCwere investigated. The microstructure, grain size and phase compositions of TiAlCsubstrate didn’t change after oxidation, hence the oxide removed TiAlCsubstrate maintained its initial flexural strength and hardness. However, the flexural strength of oxide retained TiAlCdecreased by about 5%. Acoustic emission monitoring indicated that during the process of three-point bending test, the formed AlOscale on TiAlCsurface fractured firstly in a cleavage manner, then the substrate/oxide interface cracked,and finally the TiAlCsubstrate fractured. The mechanical degradation was caused by the preferential formation of cracks in brittle AlOscale 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 AlOscale on the surface of TiAlCsubstrate.