AbstractThermal analysis, metallography, and electron-probe microanalysis have been used to corroborate one of the conflicting constitutions of the AuSn–Pb–Sn partial ternary system. The phase equilibria consist of two ternary transition reactions at 13–0Au, 48–0Pb, 39–0Sn at.-%, 275°C and 8–5Au, 28–0Pb, 63–5Sn at.-%, 210°C, and a ternary eutectic at 3–5Au, 20–0Pb, 76–5Sn at.-%, 177°C. The solubility of Pb in the ternary system is substantial and between 275 and 177°C the system can dissolve up to 4 at.-% Au and 27 at.-%Sn. The maximum width of the AuSn primary phase field in the partial AuSn–Pb–Sn system is approximately 3 at.-%. and that of Sn approximately 2 at.-%.MST/82