Enhanced deformability through interface and structure tailoring in immiscible metal matrix composites: a case study of W–Cu

Abstract

The W–Cu composite, a representative of immiscible metal matrix composites (MMCs), plays a crucial role in fields requiring both mechanical and physical properties. However, the weak interfacial bonding capability between the immiscible phases lead to poor mechanical response. In present work, a considerable interpenetrating diffusion layer and an atomic bonding interface (termed as the 3D interface) with a considerable thickness of ∼10 nm was constructed through the introduction of negative mixing enthalpy elements. Additionally, a partially recrystallized (PRX) heterogeneous matrix was built through precise thermomechanical processing (TMP) treatment. The presence of the 3D interface and PRX structure created additional space for dislocation storage, leading to a high level of heterogeneous deformation-induced (HDI) stress. On one hand, intensified activation stress was triggered for twinning in the face-centered cubic (FCC) matrix, promoting twin-mediated dynamic recrystallization (TDRX) during tensile deformation and effectively alleviating stress concentration. On the other hand, the resulting long-range internal stress not only induced large-scale abnormal twinning and phase transformation at the interface, enhancing work-hardening capacity, but also significantly improved load transfer across the W/Cu interface. In addition, the abundant sub-grain structures and free dislocations induced by rolling deformation promote the plasticization of W particles. Consequently, the composite subjected solely to straightforward infiltration and TMP (including hot rolling, warm rolling, and cold rolling) achieved a remarkable enhancement in both strength and ductility, with the cold-rolled sample exhibiting an ultrahigh tensile strength-ductility combination (1290 MPa, 8.5 %), representing a 2–3 times enhancement over conventional W–Cu composites. This work elucidates nanoscale interface–dislocation interactions in MMCs, shedding new light on the development of structure-function-integrated materials.