Strong and ductile bicontinuous Cu-RHEA composites formed by liquid metal dealloying

Abstract

Inter-granular etching often leads to ‘weakened grain boundaries’, which deteriorate the ductility of (nano-) composites or porous materials fabricated by liquid metal dealloying (LMD). In this paper, we report that inter-granular etching can be suppressed by the addition of Zr in Ti-Ta precursor, while it is dealloyed in liquid Cu. This procedure removes grain-boundary-like defects in obtained bicontinuous Cu-Ta composites, and improve their ductility in tension. By replacing Ta with a refractory high entropy alloy (RHEA), i.e. MoNbTaVW, we also obtain high-quality bicontinuous Cu-RHEA composites with low density, high tensile strength and excellent ductility. The suppression of inter-granular etching, which is essential to the mechanical stability of LMD-made materials, might arise from the decrease of grain boundary energy of Ti-Ta precursor alloys induced by Zr addition. New materials developed in this study may enable novel applications by enlarging the property space and overcoming the poor malleability and machinability of conventional materials of this type (such as Cu-W composites).