MICROSTRUCTURE AND MECHANICAL PROPERTIES OF NANO MODIFIED CERMETS

The microstructure and mechanical properties of nano TiN modified TiC based cermets(nano modified cermets) have been discussed. Results reveal that the microstructure still consists of a ceramic phase and a metal phase, and the coarse ceramic phase in the microstructure exhibits a core/shell structure, i.e. the coarse ceramic phase generally consists of a Ti(C,N) core surrounded by a shell ("SS" phase). TEM observations show that nano TiN grains are generally distributed at the interfaces of two phases or three phases. The microstructure of nano modified cermets becomes finer with increasing the amount of nano TiN addition, and the fining effect can be related to the distribution of nano TiN at the interfaces of TiC/TiC and the inhibition of the growth of TiC grains. Bending tests show that the bending strength will reach a maximum value when the amount of nano TiN reaches 8wt%. Fracture photograph shows that intergranular fracture is the main failure mode.