Microstructure, fracture behavior, and wear resistance of cellular Ti(C,N)‐based cermets

Abstract

Herein, using pre‐granulation method and subsequent vacuum sintering, cellular Ti(C,N)‐based cermets with various particle sizes of hard phase in agglomerates were prepared. As the particle sizes of added Ti(C,N) powders decreased, the interface between the matrix and agglomerates developed into clear and the number of abnormally grown grains decreased. The original shape of the agglomerates was maintained most completely and formed the most obvious cellular structure with the matrix in cermets sintered at 1420°C. Combined with the fractal dimension, the fracture behavior of cellular cermets was comprehensively analyzed to confirm the changes of mechanical properties. From cermet A to cermet D, the proportion of transgranular fracture in the matrix reduced, and intergranular fracture and tearing ridge within the agglomerates could be more clearly observed. Crack propagation exhibited additional crack deflection and bridging close to the interface, which consumed considerable amount of fracture energy. Furthermore, the fractal dimension of the fracture morphology and crack propagation path of cermet C reached a maximum indicating that the fracture behavior was extremely complex and irregular, resulting in excellent strength and toughness. The wear behaviors of cermets were analyzed at both room and high temperature, respectively. The wear rates of cellular cermets greatly reduced because the binder phase with large mean free path in the agglomerates was difficult to be squeezed out and the hard phase was hard to fall off. Overall, the cellular cermet C demonstrated the appreciably comprehensive mechanical properties and excellent wear resistance.