Effects of hot extrusion on the microstructure and tensile properties of (TiBw-TiB_2p)/2024Al composites with layered architecture

Nacre-inspired (TiBw-TiB_2p)/2024Al aluminum-matrix composites (AMCs) were fabricated using the pressure infiltration of molten Al into a porous TiBw-TiB_2ppreform obtained by ice templating. Hot extrusion (475–520 °C) was utilized to control the nacre-inspired architecture and tailor the tensile properties of the nacre-inspired AMC. The continuous ceramic-rich layers transitioned to quasi-continuous ones after hot extrusion. As the extrusion temperature increased, the thickness of the ceramic-rich and Al layers decreased from 27.2 and 25.4 μm in the cast composite to 12.8 and 11.6 μm, respectively, in the composite extruded at 520 °C. The Al composite extruded at 520 °C exhibited an optimal balance between strength and ductility, with tensile strength and elongation reaching 470.5 MPa and 1.9 %, respectively, which was 21 % and 660 % higher than that of the cast composite. The improved strength and ductility of the high-volume Al composites (over 20 vol%) were attributed to the quasi-continuous architecture, which improved the plastic deformation ability of the ceramic-rich layers. For the composite extruded at 520 °C, the quasi-continuous architecture resulted in a back stress of up to 235 MPa higher than that of composites extruded at lower temperatures, accounting for 54 % of the flow stress. Additionally, the quasi-continuous architecture coordinated plastic deformation, mitigating the premature appearance of stress concentrations. This study provides a useful approach to enhancing the mechanical properties of nacre-inspired composites produced via ice templating, thereby broadening the range of applications for this technique.