Thermomechanical processing and mechanical behavior of Kirigami-structured aluminum/titanium sheet composites

This study introduces a novel Al–Ti sheet composite concept in which pre-cut titanium kirigami inlays are integrated by thermomechanical processing to create a reinforcing architecture and locally modify the Al/Ti interface. Three- and five-layer composites were produced from EN AW 1050 aluminum and Grade 2 titanium by hot roll bonding, followed by cold rolling and selected heat treatments. Their microstructures were examined by optical and electron microscopy combined with EDS analysis, while mechanical performance was assessed by impact bending, three-point bending, and ball indentation tests. Relative to reference aluminum, the kirigami-reinforced composites exhibited substantially higher strength and energy absorption. All configurations showed a 0.2% offset flexural yield stress of at least 160 MPa after annealing. Three-layer composites reached specific absorbed energies of 1.4–1.5 J/mm and maximum flexural stresses up to 209 MPa, whereas five-layer architectures achieved 2.7–2.9 J/mm and 235 MPa, respectively. Prolonged heat treatment primarily increased the flexural yield stress through interface modification, while increasing the number of kirigami layers improved post-yield deformation behavior and energy absorption. The results demonstrate that combining kirigami architecture with thermomechanical processing provides a new route for tailoring load transfer, interface evolution, and the strength–deformability balance of lightweight Al–Ti composites with a density of approximately 3.1 g/cm³ .