A three-dimensional intertwined fiber architecture enables exceptional strength–conductivity synergy in immiscible Cu–Fe systems

The simultaneous achievement of high mechanical strength and electrical conductivity in immiscible metal systems remains a persistent materials design challenge, primarily due to limited phase compatibility and interface-induced electron scattering. In this work, a fiber-architecture-based design strategy is proposed to address this limitation in Cu–Fe composites. By constructing an Intertwined Continuous Fiber Architecture (ICFA), a three-dimensional and isotropic network is realized in which continuous Fe fibers are spatially integrated within Cu matrix. As a result, the composite exhibits a notable combination of properties, reaching an ultimate tensile strength of approximately 565.8 MPa alongside an electrical conductivity of about 85.2% IACS, with a relative density approaching full densification. This exceptional performance is attributed to the synergistic effect of continuous load-bearing Fe fibers and an uninterrupted Cu network that preserves efficient electron transport. The findings highlight phase connectivity, rather than phase fraction, as the governing parameter in optimizing multifunctional performance in immiscible systems. The ICFA strategy offers a new design paradigm for engineering high-performance metal matrix composites with simultaneously enhanced mechanical and functional properties.