Microstructure and mechanical properties of Al2O3–Ti(C,N)–cBN composites prepared by a novel hot‐forging process

Abstract Al 2 O 3 –cBN has received considerable attention in the field of ceramic cutting tools due to its high hardness, high wear resistance, and low cost, but poor interfacial bonding affects the performance of the composite. In this study, a novel hot‐forging process was used to prepare high‐performance Al 2 O 3 –cBN composites using Ti(C,N) as a binder. The evolution of the morphology, phase, and microstructure of the hot‐forged Al 2 O 3 –Ti(C,N)–cBN composites was determined, and the mechanical properties were measured. The relative density of the composites increases significantly after hot forging, and the deformation of the composites increases with the hot‐forging temperature. The highest performing Al 2 O 3 –Ti(C,N)–cBN composite was prepared by hot forging at 1600°C and has a hardness of 20 GPa, a bending strength of 647 MPa and a fracture toughness of 5.37 MPa m 1/2 , which are superior to those of a directly hot‐pressed sintered composite. However, at hot‐forging temperatures higher than 1700°C, Al 5 O 6 N and TiB 2 are formed in the composite. In the composite hot forged at 1800°C, serrated grain boundaries promote the strength and toughness of the composite to 877 MPa and 6.76 MPa m 1/2 , respectively. Therefore, the novel hot‐forging process is expected to enhance material properties.