Gradient alternating deformation mechanism of two metals and interface bonding mechanism of cu/Al cold rolling composite process

Cu/Al clad plates, with a reduction of 51%, were prepared by cold roll bonding (CRB). The bonding process, microstructural evolution, and bonding mechanism, in the rolling deformation zone of the clad plate, were studied. The interface of the deformation zone was analyzed qualitatively by experimental and numerical simulation methods. The results show that the two metal layers underwent gradient alternating deformation after the metal components enter the roll gap, grain refinement, grain boundary strengthening, and dislocation strengthening occur successively in the metal layers. Strong frictional shear stress at the interface has been produced by the gradient alternating deformation of the metal layers, which accelerated the fracture of the brittle layers of the interface. From the microscopic morphology of the shear sections, many fresh metal areas have been exposed on the surface of the metal layers before the interface began to bond. It can be seen that the cracking of the brittle layers of the metal surface and the bonding process of the interface were not simultaneous. During the cold roll bonding process, the interface undergoes the following stages: (1) brittle layer fracture; (2) fresh metals are squeezed into cracks; (3) fresh metals begin to contact with each other; (4) cracks propagation, sufficient and effective contact between fresh metals; (5) a large number of atomic vacancies are generated and the interface is firmly bonded.