Microstructures of Directionally Solidified Al–Ag–Cu Ternary Eutectics

Different three-phase microstructures are observed in directionally solidified Al–Ag–Cu ternary eutectics composed of an Ag2Al, an Al2Cu and a solid solution a-Al phase. Asurvey fromregular to irregular structures is given and some special, newstructural defects are observed and discussed. An approach for the quantitative description of the rich variety of complex three-phase microstructures is suggested including the defects. Shape factor and specific surface area of the phase particles are determined and compared for different microstructures

3D Synchrotron Imaging of a Directionally Solidified Ternary Eutectic

For the first time, the microstructure of directionally solidified ternary eutectics is visualized in three dimensions, using a high-resolution technique of X-ray tomography at the ESRF. The microstructure characterization is conducted with a photon energy, allowing to clearly discriminate the three phases Ag2Al, Al2Cu, and α-Aluminum solid solution. The reconstructed images illustrate the three-dimensional arrangement of the phases. The Ag2Al lamellae perform splitting and merging as well as nucleation and disappearing events during directional solidification