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 + Au2Bi). Schematic representations of the ternary equilibria are given.