Microstructure and mechanical properties of highly biomimetic brick-and-mortar structure Ti6Al4V/Al3Ti metal-intermetallic laminate composite

Abstract

The brick-and-mortar structure of shell nacre allows for the simultaneous enhancement of strength and plasticity through the synergistic effect of multiple toughening mechanisms at different scales. In this work, a novel nacre-like brick-and-mortar structure Ti6Al4V/Al3Ti metal-intermetallic laminate (BMS-MIL) composite was successfully fabricated via vacuum hot pressing sintering method. The BMS-MIL composite is mainly composed of Al3Ti and Ti phases, with a small amount of Al2Ti and AlTi phases. Al3Ti is in the shape of polygonal platelet, and a 5–8 μm diffusion layer composed of Al2Ti and AlTi is distributed on the surface of the platelets. Ti6Al4V connects the platelets and is present in a continuous network frame structure. Compared with the layered structure Ti6Al4V/Al3Ti metal-intermetallic laminate (LS-MIL) composite, the fracture strain of BMS-MIL composite increases by 125.1% while maintaining high strength under load perpendicular to layer, and the compressive strength of BMS-MIL composite increases by 26.3% under load parallel to layer, respectively. Material isotropy in compressive properties has been significantly improved. In bending tests, the strength of the BMS-MIL composite is 1.9 times that of the LS-MIL composite. The brick-and-mortar structure’s excellent strengthening and toughening effect benefits from the enhancement of its crack constraint.

Keywords

• Metal-intermetallic laminate composite
• Brick-and-mortar structure
• Mechanical properties
• Microstructures
• Toughening mechanism