Microstructural and Electrical Properties of Copper–Titanium Alloy Dispersed with Carbon Nanotubes via Powder Metallurgy Process

Abstract

Microstructural and electrical properties of powder metallurgy (P/M) copper alloy with carbon nanotubes (CNTs) were investigated. The Cu–0.5 mass% Ti pre-alloyed powder (Cu–0.5Ti) was made by water atomization process. The powders coated with un-bundled CNTs by using the zwitterionic surfactant water solution containing CNTs were consolidated at 1223 K in vacuum by spark plasma sintering, and then extruded at 1073 K. The P/M Cu–0.5Ti alloy without CNTs (monolithic alloy) had 202 MPa yield stress (YS) and 42.5 International-Annealed-Copper-Standard % (IACS%) conductivity. The extruded Cu–0.5Ti composite alloy containing CNTs revealed small decrease of YS compared to the monolithic Cu–0.5Ti alloy. On the other hand, the composites indicated a higher electrical conductivity than that of the monolithic alloy. For example, Cu–0.5Ti with 0.19 mass% CNTs showed 175.8 MPa YS and 83.5 IACS% conductivity. In the case of the Cu–0.5Ti composite with CNTs, the intermetallic compounds such as Cu₄Ti and TiC were observed around CNTs by TEM-EDS analysis. The amount of the solid solute Ti in the above Cu–0.5Ti composite alloy matrix was 10% of the monolithic Cu–0.5Ti alloy, and resulted in the remarkable increment of its electrical conductivity due to the decrease of solid solute Ti content.