Influence of arsenic, antimony and phosphorous on the microstructure and corrosion behavior of brasses

The effect of minor additions of As, Sb and P on phase distribution and corrosion behavior has been studied in brasses. The alloys investigated were 60Cu-39Zn-1Pb, 48.95Cu-45Zn-5Pb-1Sn-0.05As, 48.90Cu-45Zn-5Pb-1Sn-0.05As-0.05Sb and 48.85Cu-45Zn-5Pb-1Sn-0.05As-0.05Sb-0.05P. Immersion tests in 1% CuCl2 solution indicated that the addition of As improved corrosion resistance while the combined addition of As + Sb and As + Sb + P was not beneficial. The hardness increased significantly with the addition of As, Sb and P. Microstructural observations indicated an increase in beta phase fraction in the As, Sb and P containing alloys. X-ray diffraction studies confirmed the formation of intermetallic compounds in As, Sb and P containing alloys. Based on the microstructural observations, the intermetallic compounds appear to be primarily precipitated in the beta phase with As + Sb and As + Sb + P additions. The lower corrosion resistance of the alloys 48.90Cu-45Zn-5Pb-1Sn-0.05As-0.05Sb and 48.85Cu-45Zn-5Pb-1Sn-0.05As-0.05Sb-0.05P has been related to increase in beta phase volume fraction and precipitation of intermetallic compounds in the beta phase.