Part VII - Papers - The Microstructure and Crystallography of the Aluminum-Germanium Eutectic

Specitlrens of the Al-Ge eutectic alloy have been frozen unidivectionally at rates between 2.5 x 10-6 and 2.5 x 10-4 cm per sec and the structure examined by optical and X-ray methods. There is no epitaxial relationship between phases, the aluminum having random orientation and the germanium a preferred (011) fiber textuve. Lamellar colonies which are BINARY eutectic alloys occur between either silicon or germanium with the metals aluminum or silver. common in this alloy are constructed from axial and nonaxial (111) plates of germanium which are related by a variety of twin configurations. Irregular or globular regions of the microstructure are composed of continuous single crystals of each phase, the germanium being heavily twinned. There is limited solid solubility in these systems, and the eutectic phases all involve diamond cubic with fcc crystal structures. In the microstructures of these eutectic mixtures the silicon and germanium crystals exhibit an almost infinite variety of shapes which are notably sensitive to