Influence of strong carbide-forming elements (Nb and Ta) on the development of the green (Ti, Me)(C,N)-high chromium Fe-based cermets

In this work, 70 wt% Ti(C,N)- high chromium Fe-based green cermets with the addition of Nb and Ta alloying elements were fabricated through pressureless vacuum sintering. The effects of Ta and Nb addition with varying content on the phase constituents, microstructures, and mechanical properties of the (Ti, Me)(C,N)-FeCr cermets were studied in detail. Cermets with high-chromium ferrous binders face the challenge of the formation of secondary chromium-rich carbides, thus reducing the chromium content of the binding metal. The present work addresses the effect of strong carbide-forming elements, in particular Ta and Nb, on the structure formation of high-chromium Fe-bonded (Ti, Me)(C,N)-FeCr cermets. Using thermodynamic equilibrium calculations, the microstructural investigation was supported by predictions of the compositions of the constituent phases as a function of Ta and Nb additions. The addition of Ta and Nb alloying elements generated (Ti, Me)(C,N) (Me = Ta and Nb) solid solutions and MxCy x C y (M = Fe, Cr) intermediate complex carbide phases during the reaction process, and refined Ti(C,N) particles significantly. The addition of strong carbide-forming elements enables the reduction of chromium depletion in high-chromium (Ti, Me)(C,N)-FeCr cermets. The strengthening mechanisms of (Ti, Me) (C,N)-FeCr cermets were mainly solid solution strengthening, and grain refinement strengthening.