Microstructure and mechanical properties of ultrafine Ti(CN)-based cermets fabricated from nano/submicron starting powders

Starting from commercial nano/submicron raw powders, ultrafine grade (mean grain size less than 500 nm) titanium carbonitride (Ti(CN))-WC-Mo-Ni/Ni + Co-C cermets systems were fabricated and their microstructures as well as mechanical properties were characterized, tested and compared with coarse (micron-sized) cermets. Study shows that different raw materials and initial powder particle size play a critical role in determining cermets' microstructure and mechanical properties. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) in combination with energy dispersive X-ray analysis (EDX) reveal that various cermets systems present quite different morphological and structural characteristics. The reasons why these differences come about were discussed and the formation mechanism of a new type core/rim structure (white core and grey rim) was proposed too. Mechanical property testing was conducted and was related to the microstructural features.