Influence of Ce-Co pre-alloyed powder addition on the microstructure and mechanical properties of Ti(C, N)-based cermets

A series of cermets with the varying nominal composition Ti(C-0.7 NO3)-WC-MO2C-TaC-(Co, Ni)-x(Ce-Co) were prepared via low pressure sintering, to investigate the effect of Ce-Co pre-alloyed powder addition on the microstructure and mechanical properties of Ti(C,N)-based cermets. The Ce-Co content was varied between 0 and 0.8 wt.%, in 0.2 wt.% increments. Experimental results show that the addition of trace Ce-Co pre-alloyed powder can favor the microstructure refinement, improve the particulate dispersion and promote the dissolution of various carbides in binder phase. In addition, energy-dispersive X-ray analysis revealed rare earth cerium was dissolved in the Co/Ni binder, and then the complex solid solution phase containing cerium was formed during the liquid sintering process. The modified microstructure and phase composition by adding rare earth cerium in the form of cobalt pre-alloyed powder results in the high mechanical properties of the cermets. Compared with undoped sample, the cermets doped with 0.6 wt.% Ce-Co pre-alloyed powder showed optimum comprehensive properties: the transverse rupture strength of 1989 MPa, Rockwell hardness of 93.1 HRA and the fracture toughness of 11.01 MPa m(1/2), respectively. (C) 2012 Elsevier Ltd. All rights reserved.