THE TERNARY-SYSTEM AU-NI-SN

The phase relations in the Au-Ni-Sn system have been examined by powde r 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 th e phase diagram at 400 degrees C. Au and Ni can scarcely be mutually e xchanged in most of the phases, but a continuous range of solid solubi lity seemingly occurs between AuSn (delta) and Ni3Sn2 (gamma). The max imum variation in the Sn content for this phase is found to be ca. 5 a t%, for mole fractions between n(Ni)/(n(Au) + n(Ni)) = 0.7 and 1.0. Th e only genuine ternary phase in the system, labeled A, takes the virtu ally stoichiometric composition AuNi2Sn4 and exists at 400 degrees C. (C) 1996 Academic Press, Inc.