CONTAINERLESS SOLIDIFICATION OF EUTECTIC PbSn ALLOY DROPLETS IN A DROP TUBE

摘要

Containerless solidification of 300 to 850 um diameter droplets of PbSn eutectic alloy was achieved by using a 3m length drop tube, which is one of the most suitable and low cost option to provide a microgravity environment on the ground. Phase morphology and composition were investigated, respectively, by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). It was found that the microstructure of the droplets depends on their sizes, where in larger diameters (>500μm) consists of both regular lamellar and irregular structures, and on other hand, for the smaller ones (<500μm) the structure is only irregular with higher lead concentration.