Phase equilibria in the Ag–Au–Bi ternary system

The aim of the action of Cost 531 taking into account the 11 elements: Ag, Au, Bi, Cu, In, Pb, Sb, Sn, Zn (solder), Ni and Pd (substrate) is the database assessment of candidates for lead free soldering process. Among those elements, we chose to study three of them forming the ternary Ag–Au–Bi system. We have determined its phase diagram using X-ray powder diffraction, differential scanning calorimetry and electron probe micro-analysis. Four vertical sections (isopleths) were studied at 20 at.% Ag, 50 at.% Bi, 85 at.% Bi and the section with ratio Ag:Au = 1:4. The results give one transitory peritectic reaction and an extremely large primary crystallization area, L + α, restricting thus the two others reactions (L + (Bi) and L + Au 2Bi). Schematic representations of the ternary equilibria are given.