Simultaneously enhancing fracture toughness and strength in a hierarchical nanolamella-structured alloy

In general, strength and fracture toughness are mutually exclusive in most structural materials. Here, we report a simultaneous enhancement of both the strength and fracture toughness in a hierarchical nanolamella-structured TiZrAlV that consists of lamellae with nano- and submicrometer-sized widths together with a few submicrometer- and micrometer-sized grains. The hierarchical nanolamella-structured alloy shows an excellent combination of high yield strength (σs~1438 MPa) and fracture toughness (KIC~57 MPa m1/2) as compared with its coarse-laminated counterpart. The high strength results from a lot of nanoscale lamellae in the alloy, and the enhanced fracture toughness can be attributed to both the coarse α lamellae and grains that have a high strain hardening capability and the complex strain paths caused by a hierarchical nanolaminated structure, which may enhance the resistance to crack growth and change the crack path during fracture processes.