Morphological characterization of the Al–Ag–Cu ternary eutectic

Abstract

Ternary eutectic microstructures have a level of complexity far exceeding that of binary eutectics. As there is currently no detailed description of ternary eutectic structures in the literature, we have undertaken a systematic investigation of the structures formed by directional solidification of the ternary eutectic Al – Ag – Cu. Using a constant temperature gradient of 3 K mm–1and solidification velocities between 0.2 and 5 µm s–1, we are able to observe different forms of the eutectic structure with varying degrees of alignment. We describe these structures both qualitatively and quantitatively, using measures including the volume fraction and composition of all phases, the distribution of interphase separations, and the number of nearest neighbor phases. The effects of solid-state transformations on the microstructure are also discussed.