Phase equilibria in the Ag-Ni-Sn system: Isothermal sections

The ternary system Ag-Ni-Sn is one of the constituents of the quaternary system Ag-Cu-Ni-Sn, which is of interest for the investigation of the interactions of Ag-Cu-Sn solder alloys with Ni as a substrate. Until now, only limited research has been done on the Ag-Ni-Sn system, especially in the (Ag,Ni)-rich part, most probably due to experimental difficulties caused by the monotectic reaction in the Ag-Ni binary system, which extends far into the ternary. In the present work a comprehensive study of the phase equilibria in four isothermal sections of the Ag-Ni-Sn system at 200, 450, 700, and 1050 degrees C was carried out employing X-ray diffraction (XRD), metallography, and electron probe microanalysis (EPMA). No evidence for the existence of a ternary phase was obtained, and, in most cases, ternary solubilities of the binary phases were found to be insignificant. The liquid miscibility gap at high temperatures caused a number of serious experimental problems during sample preparation.