Led by Amber Genau

FIB2Ternary eutectics exhibit a level of complexity far beyond that found in binary eutectics.  This project aims to better understand the fundamentals of metal solidification through the use of these special structures, while also developing new methods for quantifying complex microstructures.

Standard binary eutectics form either as alternating lamellar sheets or as rods within a continuous matrix.  These structures have been extensively studied and are generally well characterized.  However, in multi-component systems, however, it is possible for three phases to form simulaneously from the liquid, producing ternary eutectic microstructures which can assume a much wider variety of configurations and which have been studies relativley little.  Ternary eutectics provide a natural starting point for exploring the solidification patterns and microstructure formation in the multi-component, multi-phase systems which are so critical to today's advanced materials applications.

For this project, led by Dr. Amber Genau, Al-Cu-Ag samples at the eutectic composition are prepared in a special directional solidification furnace.  Samples are analyzed in both the longitudinal and transverse directions using optical and scanning electron microscopy.  A variety of morphologies have been observed, and wor in underway to determine the factors which affect microstructure selection.  Electron backscatter diffraction (EBSD) is being used to determine the crystal orientation of the different phases and the orientation relationships between them.  Novel methods of quantifying these complex structures are being explored as well, such as number of adjacent phases and relative fraction of interfacial area.  Three-dimensional analysis of these samples is planned. 

3eutectics Example of three eutectic morphologies found on the same cross section of the same sample. White phase is
           Ag2Al, light gray phase is Al2Cu, and darker phase with precipitation is solid solution aluminum.