Growth and solid/solid transformation in a Ni-Si eutectic alloy

High temperature structural components demand materials that maintain satisfactory mechanical and chemical characteristics. These needs may be met by applying some eutectic alloys, including Ni-Ni3Si. This paper deals with the directional solidification of Ni-Ni3Si grown under several growth rates. The analysis of the eutectic microstructure was carried out using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The results obtained provided a precise analysis of the Ni3Si phase. It could be noticed that the solid/solid transformations by which Ni3Si phase goes through, deeply affects its morphology. In addition, quantitative information on the eutectic structure was obtained. It was confirmed that the growth rate variation deeply affects the final microstructure as it influences the efficiency of atomic diffusion along the solid/liquid interface.