Fabrication of Al/Al-TiB2 laminate composites via hot press sintering process: An insight into the mechanical properties and fracture behavior

The Al/Al-TiB2 laminated composites with different numbers of layers was fabricated by hot press sintering method. The results show that Al/Al-TiB2 interface is well bonded without obvious micropores, cracks, or other defects, while the stacking faults and dislocation loops are observed at the interface. The average grain sizes of Al and Al-TiB2 layers are 45.17 and 5.51 mu m in the composite with 3 layers, while they greatly increase to 80.07 and 6.51 mu m in the composite with 5 layers. The hardness increases gradually along Al layer, Al/Al-TiB2 interface, and Al-TiB2 layer. TiB2 particles mainly contributes to the enhancement of bending strength, and the maximum strength of 110.0 MPa is achieved in the composite with 3 layers due to the fine grain size, small particle spacing, and more geometrically necessary dislocations in Al-TiB2 layer. During bending deformation, Al layer exhibits ductile fracture with shear lip, slip band, fatigue striation and dimple, while Al-TiB2 layer shows typical brittle fracture with micro-voids and cleavage. The stress concentration and crack always appear in Al-TiB2 layer, while Al layer can transfer strain and inhibit strain localization. An increasing ductility of the laminated composites is achieved due to crack deflection, interfacial delamination, and strain transferring.