Enhanced strength-ductility synergy of Al/Zn/Al laminated composite with unique interface and multi-modal heterogeneous microstructure

Laminated bimetal composites have become an important strategy for designing and manufacturing desirable metallic components. Here, Al/Zn/Al laminated composite was fabricated by porthole die co-extrusion (PDCE) process, offering excellent mechanical performance. An obvious transition zone with a dispersed duplex structure (alpha and eta phases) instead of intermetallic compounds was formed in Al/Zn interface due to element inter-diffusion and eutectoid transformation. The alpha/eta phase interface showed a 3D characteristic with compositional and structural gradients. Moreover, Al/Zn/Al composite displayed a multi-modal heterogenous structure including the typical macroscopic hierarchical structure by alternately stacking Al and Zn layers with different microstructures, the gradient structure from Al/Zn interface to the center of Al or Zn layer, and the bimodal structure formed either near Al/Zn interface or in the layer center. As a result, Al/Zn/Al composite exhibits superior mechanical performance compared with the individual component (Al or Zn) and a satisfactory balance between strength and ductility.