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 degrees 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 (delta) and Ni3Sn2 (gamma). The maximum variation in the Sn content for this phase is found to be ca. 5 at%, for mole fractions between n(Ni)/(n(Au) + n(Ni)) = 0.7 and 1.0. The only genuine ternary phase in the system, labeled A, takes the virtually stoichiometric composition AuNi2Sn4 and exists at 400 degrees C. (C) 1996 Academic Press, Inc.