2018 Volume 59 Issue 11 Pages 1747-1752
Typically, bismuth added in traditional Cu–Zn brass segregates as films or particles along the alpha-beta phase boundary and induces cracks after casting. The present work investigated the bismuth formation in lead-free Cu–Zn–Si yellow brass with various amounts of recycled bismuth–tin (Bi–Sn) solder. The results showed that no bismuth film segregated at the phase boundaries. In contrast, round particles of bismuth formed in the beta phase and at the alpha-beta phase boundaries when added 1 mass% Bi–Sn alloy and the bismuth particles embedded only in the alpha phase when added 2 to 4 mass% Bi–Sn alloy, respectively. The morphology of the fracture surfaces was significantly modified when Bi–Sn alloy content was increased. More importantly, there was no crack observed in as-cast samples and samples did not subject to any heat treatment process unlike the bismuth formation in other work. Thus, this work suggests that the addition of recycled Bi–Sn solder in lead-free Cu–Zn–Si yellow brass is beneficial to avoid cracks in castings and offer an original lead-free brass alloy with superior properties.
