Effect of pre-solid solution treatment of secondary carbides on the microstructure and mechanical properties of Ti(C,N)-based cermets

Abstract

Promoting favorable wettability between the ceramic hard phase and the metal binder phase is crucial for attaining desirable properties in Ti(C,N)-based cermets, wherein the presence of a typical core-rim structure plays a critical role. In this work, two pre-solution powders were synthesized using carbon thermal reduction technology to replace single or less-component of carbides while keeping the nominal composition unchanged. Employing thermal stability analyses of pre-solid solution powders, the effect of pre-solid solution treatment on the microstructure and mechanical properties of cermets were investigated. Results showed that (Ti,W,Ta,Mo)C exhibits higher thermal stability and accelerates the metallurgical reactions compared with (Ti,W,Ta)C. Thicker rim phase and less rimless-black-core grains formed with the increase of component in the solid solution powders, because of the significantly retarded dissolution of high-thermal-stability solid solution carbides in the binder phase. Under identical conditions of composition and sintering process, the attainment of optimal comprehensive mechanical performance in Ti(C,N)-based cermets was achieved through the strategic incorporation of (Ti,W,Ta)C dopants. It indicates that a suitable pre-solid solution treatment for secondary carbides can further improve the performance.

Keywords

• Ti(C,N)-based cermets
• Core-rim structure
• Pre-solid solution treatment
• Thermodynamic stability
• Mechanical properties