Effect of ethanol on the formation and properties of a Cu-NbC composite

Copper (Cu), niobium (Nb) and graphite (C) powders were used as starting materials to produce an in-situ Cu-15 vol% NbC composite using mechanical alloying followed by spark plasma sintering (SPS). A mixture of Cu, Nb and C powders was milled in an argon atmosphere for 30 h. Different amounts of ethanol were used to study the effect of the process control agent on the formation of NbC and the consequent properties of the Cu-NbC composite. The results showed that NbC was formed in the copper matrix during ball milling when the powders were milled with 0-2 wt% ethanol, whilst the powder milled with 5 wt% ethanol only exhibited NbC formation after sintering. The as-milled powders were then sintered using SPS at 1000 °C, an applied pressure of 100 MPa and soaking duration of 15 min. As a result, the best combination of properties was observed in the sintered Cu-15 vol% NbC composite using a powder milled with 1 wt% ethanol, viz. electrical conductivity of 24% IACS, microhardness of 377 Hv and relative density of 97%.