Fracture origin and intrinsic strength of ultra-fine TiC_(0.7)N_(0.3)-based cermet

摘要

Transverse rupture strength of Ti(C,N)-based cermets is largely affected by the fracture origins. In this paper, ultra-fine cermet of low binder content is prepared with 0.13 mu m TiC_(0.7)N_(0.3) powder, and the fracture origin of the cermet is studied. The results show that the oxygen content of the ultra-fine TiC_(0.7)N_(0.3) powder can be decreased by heating it in vacuum sintering furnace; 90 percent of the fracture origins are pores, and there are also a few Ni pools and carbide aggregations. The intrinsic strength of the prepared ultra-fine TiC_(0.7)N_(0.3)-based cermet is calculated to be 5000 MPa, much larger than the measured transverse rupture strength; HIP process can decrease the size of pores, and improve the transverse rupture strength of ultra-fine TiC_(0.7)N_(0.3)-based cermet.