Effect of Heterogeneous Ti Layers on Mechanical Properties of Cu/Ti Laminated Sheets Prepared by Accumulative Roll Bonding

Abstract

Cu/Ti laminated sheets with heterogeneous Ti layers are successfully fabricated by accumulative roll bonding (ARB). The microstructure during processing is characterized by scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). During the deformation of the constituent metals, the hard Ti layers neck preferentially but with a continuous layered structure. Upon four ARB cycles, there are five Ti layers with different microstructure states and grain sizes (from 1.3 to 0.5 μm) in the ARB4 sample. Tensile test of ARB4 sample indicates excellent comprehensive mechanical properties, compared with pure Cu and pure Ti, it has higher ultimate tensile strength (508 MPa), and the elongation (9.2%). In the result of loading–unloading–reloading test, there is a strain gradient during the tensile process due to heterogeneous existence of Ti layers, which produces a multilevel hetero‐deformation‐induced (HDI) stress strengthening and improves the coordinated deformation ability of the sample. Second, layered structure and interface with alternate strong and weak bonding can effectively hinder the propagation of cracks to outline higher strength with improved ductility. This structural design helps to prepare laminated materials sheet with excellent comprehensive mechanical properties through the ARB process.