Microstructure, fracture behavior and mechanical properties of cellular Ti(C,N)-based cermets with varying Ni contents fabricated by multiphase-flow agglomeration and subsequent vacuum sintering

Abstract

Cellular Ti(C,N)-based cermets were fabricated using multiphase-flow agglomeration followed by liquid phase sintering. The influence of the Ni binder phase content on the microstructure, mechanical properties and fracture behavior of cermets was investigated. A distinct interface between the matrix and the agglomerates was observed. As the Ni content increased, the volume percentage of the agglomerates dropped and some agglomerates began to dissolve, compromising the integrity of the structure. The TRS of cellular cermets initially elevated before decreasing. Hardness consistently declined, and toughness exhibited the opposite trend. Moreover, the relationship between the volume percentage of agglomerates and the mechanical properties of cellular cermets was modeled mathematically. From cermets A to E, there was a noticeable increase in the proportion of tearing ridges and dimples in both the matrix and agglomerates. Cracks passing through the interface were more likely to bridge or deflect, significantly consuming fracture energy. Furthermore, a larger fractal dimension indicated that the fracture behavior of cellular cermets was highly complex and irregular, contributing to superior fracture toughness. In summary, cellular cermet D containing 22 wt% Ni binder phase exhibited the highest TRS value and better hardness and fracture toughness.