Effect of oscillatory frequency on densification and mechanical properties of Al2O3-Ti(C,N) composites fabricated by dynamic sinter forging

High-performance ceramic cutting tools require superior hardness and toughness under extreme temperatures; yet conventional sintering methods for Al 2 O 3 -Ti(C,N) composites often suffer from incomplete densification and grain coarsening. In this study, dynamic sinter forging (DSF) with oscillatory pressure amplitudes of 40 ± 40 MPa at 1600 °C is employed to regulate the densification behaviour and microstructural evolution of Al 2 O 3 -Ti(C,N) composites. The composite achieves a relative density above 99.9%, flexural strength of 1111 MPa, and hardness of 24.5 GPa at 15 Hz. A maximum fracture toughness of 5.44 MPa m 1/2 is obtained at 10 Hz. Microstructural observations reveal that moderate-frequency oscillation activate interfacial diffusion and stress-assisted plastic flow, promoting grain-boundary sliding and compact bonding to form a fine-grained and homogeneous structure. These results confirm that frequency-controlled DSF facilitates simultaneous enhancement of strength and toughness, providing a valid route for fabricating high-performance Al 2 O 3 -based cutting ceramics with optimized microstructural designs.