Heterostructured copper-brass laminates with gradient transition layer

Abstract

Heterogeneous laminates are developed to address the trade-off between strength and ductility, but interface cracking is a major concern. In this work, a heterostructured copper-brass laminate with 20 layers was successfully prepared by diffusion welding + cold rolling + annealing (DRA) technique. The obtained copper-brass laminate was composed of brass layers with fine grains and copper layers with coarse grains. During diffusion welding, a transition layer was found between copper and brass layers, with composition, grain size and hardness gradient. With the help of the gradient transition layer (GTL), the bonding strength of the welding interface is so high that cannot be torn apart during peeling test. The GTL plays important role in coordinating plastic deformation and relaxing stress concentration. An excellent combination of strength and ductility was realized in the copper-brass laminates, which can be attributed to the unique GTL and high density of heterogeneous interfaces. Moreover, the GTL with hardness gradient can prevent micro-cracks from initiating at interfaces, and avoid macro-crack propagating along the welding interface or coarse/fine grained heterogeneous interface.