Simultaneously enhanced strength and ductility of W-Cu bimetallic composites assisted by continuous cellular dislocation structure

Abstract

W-Cu bimetallic composites are commonly employed in a wide range of critical fields due to their exceptional comprehensive performance. However, the weak interfacial bonding between two distinctive phases results in challenges such as easy deformation, poor mechanical performance, and short lifespan. In present work, by adopting thermo-mechanical processing (TMP) treatment, the W and Cu phases, connected by the nano-diffusion layer, underwent a cooperative deformation process. Meanwhile, the pre-existing nanoclusters anchored the accumulated dislocations during TMP, forming a unique continuous cellular dislocation structure (CC-D) with the nanoscale size of approximately 40 nm during the subsequent recovery annealing process. The CC-D dominated plastic deformation mechanism dynamically refined the grains by forming a multiscale network of stacking faults and deformation twins (SFs-DTs). Moreover, the slip transfer and twinning originating from the W/Cu interface were stimulated to alleviate interfacial stress accumulation. Thus, the ensuing strengthening and strain-hardening mechanisms maintained stable tensile flow, resulting in an exceptional strength-ductility combination (965 MPa, 14.8%). Moreover, the high density of twins within the Cu grains, with numerous coherent twin boundaries, reduced electron scattering and maintained a considerable electrical conductivity (30 %IACS) for the bimetallic composites.