Spark plasma sintering of mechanically alloyed in situ copper–niobium carbide composite

A Cu–NbC composite with high electrical conductivity and high microhardness was synthesized by mechanical alloying and densified using spark plasma sintering (SPS). Mixtures of Cu–NbC powders corresponding to volume fractions of 1, 5, 15 and 25 vol% NbC were milled in a high energy planetary mill under argon atmosphere for 30 h using ethanol as process control agent. The Cu–NbC as-milled powder was sintered using spark plasma sintering temperatures between 900 and 1000 °C. X-ray diffraction investigation showed that NbC started to form in the copper matrix during ball milling and the reaction between Nb and C was completed after 10 min of SPS sintering. Electrical conductivity and density of the Cu–15 vol% NbC composite increased with increasing sintering temperature. The results showed the superior properties of SPS-prepared Cu–NbC composite: electrical conductivity is almost 4 times higher and microhardness is 3.5 times higher than with normal sintering. A highest density of 98% and electrical conductivity of 45.6% IACS were obtained in the Cu–1 vol% NbC composite. The highest microhardness of 452.9 Hv was achieved in the Cu–25 vol% NbC composite.