EXPERIMENTAL INVESTIGATION OF WETTING CHARACTERISTICS OF Al–Sn ALLOY

This work studies the polycrystalline Al–Sn system specifically Al-20 wt.%Sn and Al-32 wt.%Sn for the grain boundary wetting transition. The wetting transition behavior was studied against varying annealing temperatures and alloy composition. The samples produced were studied for grain boundary segregation, grain boundary phase identification, and distribution using various characterization techniques. In the heat-treated samples, clear evidence of wetting transition that led to phase and structural transformations at the Grain Boundaries (GBs) was observed in the Al–Sn binary system. A thin line of wetting was observed for Al-20 wt.%Sn, while in the Al-32 wt.%Sn system, the enrichment of GBs with the liquid phase was appreciable. Additionally, the extent of wetting and associated structural changes increased with temperature. The phase diagram and X-ray Diffraction (XRD) patterns did not show the formation of any new phase after quenching. This suggests that Sn segregation in the Al–Sn alloy resulted from an insoluble Sn phase and significant differences in melting temperature and density. The XRD patterns indicated an increase in the intensity of Sn peaks with temperature, implying a higher degree of tin segregation at elevated temperatures. The differential scanning calorimetry analysis obtains a distinctive signature of the grain boundary solidus temperature.