Effects of Bi on microstructure and properties of Se-Bi brass have been investigated by microstructural analysis and tensile fracture observation.The results show that single Bi is distributed in the boundary of α phase and β phase

sharply affecting the castability of the Se-Bi brass.Particle Bi phase is distributed on the phase boundary with Bi content less than 1.0%

and the bulky Bi phase is distributed on the boundary with about 2% Bi content

moreover

continuous film occurs in the boundary with Bi content more than 2.5%.The segregation mechanism of Bi was approached based on thermo-kinetics analysis.