Soft/hard copper/bronze laminates with superior mechanical properties

In current work, various soft/hard copper/bronze laminates with transition interfaces and superior mechanical properties were fabricated by three primary processing steps: diffusion welding, cold rolling and annealing (DCA). The superior combinations of strength and ductility for copper/bronze laminates were mainly attributed to back-stress hardening induced by well-bonded transition interfaces. Back-stress hardening was affected by the microstructures and hardness ratio of soft/hard layers. High density dislocations both in original soft and hard layers can weaken the back-stress hardening (ductility). For the dislocation-free copper/bronze laminates, a reasonable high hardness ratio between hard and soft layers can generate a larger strain gradient so as to produce higher back-stress hardening. This work provides a new structural design strategy for metallic materials to simultaneously improve their strength and ductility.