A series of experiments have been designed to investigate the effect of different space positions between liquid Ag-Cu-Sn alloy drop and iron substrates on the liquid/solid inter-facial morphologies by a sessile drop method. The results show that Ag-Cu-Sn alloy diffuses into the solid iron substrate, and the amounts are greater and the distances are longer when it dif- A series of experiments have been designed to investigate the effect of different space positions between liquid Ag-Cu-Sn alloy drop and iron substrates on the liquid / solid inter-facial morphologies by a sessile drop method. The results show that Ag-Cu- Sn alloy diffuses into the solid iron substrate, and the amounts are greater and the distances are longer when it dif-