Surface and bulk characterization of molten in and In-Sn alloys

In this work a double contribution to the characterization of molten In and In-Sn alloys considered as main components of an important class of lead free solder materials is shown: the study of the influence of oxygen on the capillary phenomena and the XRD investigation of the structure of liquid in a range of temperatures around that of liquidus. The surface tension behaviour of In-Sn binary alloys at different compositions, in terms of effective oxygen pressure, were compared with the data of pure In and the theoretical predictions, revealing that the lower oxidizability of indium was shown to control indium-tin alloys with a tin content up to about 80 at%, due to the presence of the most volatile oxide In2O. From the XRD spectra the radial distribution functions (RDF) have been determined for each alloys. Experiments of High Temperature X-ray diffraction (HT-XRD) showed that atomic clustering forms in the melt immediately before the appearing of the first solid. The structure of clusters is correlated to that of solid.