Microstructure and characteristics of Cu-W composite prepared by W-coated Cu powder with different W contents

Abstract

In this study, nanometer W particles were added to Cu matrix as reinforcement phase, aiming to maintain the excellent electrical conductivity of Cu matrix while significantly improving the mechanical performance of Cu-W composite. Cu-W composite powder with W nanoparticle coated Cu was prepared after spray drying and two-step hydrogen reduction. Cu-W composite with different W contents (0 wt%, 5 wt%, 10 wt%, and 20 wt%) were fabricated by spark plasma sintering (SPS). The coating structure can refine Cu particle size and inhibit Cu grain growth during sintering. The impact of W nanoparticles on microstructure, physical and mechanical performance of Cu-W composite was studied. The average size of the W particles dispersed in Cu matrix ranged from 71.89 nm to 106.90 nm. Electron back-scatter diffraction (EBSD) statistics indicated that Cu-5 wt%W, Cu-10 wt%W, and Cu-20 wt%W composite had a mean grain size of 0.76 μm, 0.71 μm, and 0.57 μm, respectively. Cu-20 wt%W composite had a uniform W network-Cu pool structure. The room-temperature tensile strength of Cu-20 wt%W composite was up to 421.98 MPa, with an elongation of 10.91 %; and the room-temperature compressive yield strength reached 313.83 MPa, an increase of 71.76 % compared to pure Cu. Although adding W nanoparticles caused the decrease of electrical conductivity, the conductivity of all Cu-W samples exceeded 81 %. The (111) of Cu and (110) of W showed a semi-coherent relationship with a calculated mismatch parameter δ of 0.077 and good interfacial bonding. The strength of Cu-W composite was improved by the pinning effect of W nanoparticles as a result of the combined effect of fine grain and dispersion strengthening.