Effects of secondary carbides on the microstructure, mechanical properties and erosive wear of Ti(C,N)-based cermets

Abstract

The present work investigated the effects of secondary carbides (Mo2C/WC/TaC/NbC) on the microstructure, mechanical properties and erosion behavior of Ti(C,N)-based cermets. The results indicate that Ti(C,N)-based cermets with different secondary carbides have the typical core/rim microstructures which include the Ti(C,N) core phases and rim phases of (Ti,X)(C,N) solid solution (where X: Mo/W/Ta/Nb). Mo2C addition significantly refines the ceramic grain and enhances the hardness, indentation fracture toughness and transverse rupture strength (TRS) of cermets. The volume fraction of rim phase increases while the core size decreases in the cermets containing TaC and NbC. Furthermore, the considerable solubility of carbides (WC and Mo2C) in metal Ni strengthens the binder phase and decreases the thickness of brittle rim phase. The combined effects result in an increasing trend of mechanical properties in order of NbC, TaC, WC and Mo2C containing cermets. Strengthened binder, moderate thickness of rim and refined grain jointly enhances the mechanical properties of Ti(C,N)-based cermets, resulting in the improvement of erosion resistance.