Investigation of microgravity effect on solidification of medium-low-melting-point alloy by drop tube experiment

The solidification microstructure of Al-Ni, Al-Cu, Ag-Cu, Al-Pb and Cu-Co alloys quenched in silicone oil before and after free fall in evacuated 50 m drop tube were investigated contrastively. The effect of microgravity on the solidification process of medium-low-melting-point eutectic, monotectic and peritectic alloys were analyzed and discussed. The results indicated that the effects of microgravity on the eutectic cell shape, the pattern in eutectic cell and the inter-eutectic spacing were different for different types of eutectic systems; the size distribution of Pb particles in Al-5wt% Pb monotectic alloy was significantly changed by microgravity; and the shape of retained primary alpha-Co phase in Cu-10wt%Co peritectic alloy was also changed by microgravity. These results are beneficial for people to further identify and analyze the solidification behavior of multiphase alloys under microgravity.