Characteristics of Lead-Free P/M Cu60-Zn40 Brass Alloys with Graphite

Brass alloys are widely used as industrial materials because of their excellent characteristics such as high corrosion resistance, non-magnetism, and good machinability. In particular, machinable brass is obtained by adding lead. It is, however, necessary to reduce the use of lead from a viewpoint of the hazardous effects on the environment and humans. In this paper, the uniform distribution process of graphite particles into brass alloy by powder metallurgy (P/M), and machinable lead-free P/M brass with graphite additives have been described. The mixture powder of graphite particles and 60Cu-40Zn brass alloy was used as input raw materials, having mean particle sizes of 5µm and 40 µm, respectively. It was consolidated at 1053K by Spark Plasma Sintering (SPS) to then be used as the compacts for extrusion. The additive of 1 wt% graphite particles in P/M extruded brass alloys was significantly able to improve their machinability as well as the conventional brass alloys with lead.