Evolution and mechanism of crack propagation method of interface in laminated Ti/Al₂O₃ composite

Metal-Ceramic composites possess remarkable mechanical properties and chemical stability, but suffer from brittleness. Here, we prepare laminated Ti/Al₂O₃ composite via tap-casting and hot-press sintering at 1500 °C with an applied pressure of 30 MPa for 1.5 h to improve its mechanical performance. Compact laminated structure and crack deflections emerged in a distinct interfacial region were observed. The EDS and XRD results demonstrate that aluminum (Al) and oxygen (O) elements transmit through the interface to titanium (Ti) layers and react with Ti to form AleTi intermetallic compounds, titanium oxides and solid solutions of Al-Ti-O. Meanwhile, triple junction boundary emerging in interface is evaluated by Zener's relation. Finally, the schematic illustration of microstructure evolution indicates that the hybrid fracture mode (e.g. trans-granular fracture, inter-granular fracture and the co-existing mode) results in the crack deflection. Owing to this hybrid fracture method, the laminated Ti/Al₂O₃ composite invariably performs better performance than monolithic composite.