The Ternary System Au–Ni–Sn

The phase relations in the Au–Ni–Sn system have been examined by powder X-ray diffraction, metallography, electron microprobe analysis, and thermal analysis. The range of homogeneity of the various phases, tie-lines, and tie-triangles are presented for an isothermal section of the phase diagram at 400°C. Au and Ni can scarcely be mutually exchanged in most of the phases, but a continuous range of solid solubility seemingly occurs between AuSn (δ) and Ni3Sn2(γ). The maximum variation in the Sn content for this phase is found to be ca. 5 at%, for mole fractions betweennNi/(nAu+nNi) = 0.7 and 1.0. The only genuine ternary phase in the system, labeled A, takes the virtually stoichiometric composition AuNi2Sn4and exists at 400°C.