Structural characterization and mechanical properties of bicontinuous dual-metal composites prepared by liquid metal dealloying

Abstract

Most bicontinuous dual-metal composites (BDMCs) generated by liquid metal dealloying (LMD) exhibit lamellar microstructures at the grain boundaries of initial precursor alloys, resulting in little to no ductility. Herein, grain-boundary-defect-free bicontinuous Ni/Ag composites consisting of network-like dealloying structures (Ni phase) and solidified matrices of liquid metal corrosive media (Ag phase) are prepared. Then, a detailed study of their intrinsic structures and mechanical properties under uniaxial tension is conducted. This composite is found to be completely dense without visible holes or cracks. Both the Ni phase and Ag phase have independent open porous structures and are well bonded with clear interfaces, forming a dual-interlocking structure with phase-to-phase and grain-to-grain interlocking. This structure does not significantly affect the elastic modulus or tensile yield strength, but under specific conditions, it can enhance the tensile ductility because of the coordinated deformation between the two phases, thereby reducing the likelihood of stress concentration and delays necking. Moreover, these bicontinuous Ni/Ag composites display superior strain hardening rates in comparison to pure Ag. The high strength and ductility of this structure warrant the exploration of its practical application in many areas, if more defect-free systems are synthesized by optimizing the LMD process in the future.