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Microstructural evolution and mechanical properties of $Al_{71.6}Ge_{28.4}$ eutectic alloy  

Park, Jin-Man (Center for Non-crystalline Materials/Dept. of Metallurgical Eng., Yonsei University)
Yook, Wan (Center for Non-crystalline Materials/Dept. of Metallurgical Eng., Yonsei University)
Kim, Do-Hyang (Center for Non-crystalline Materials/Dept. of Metallurgical Eng., Yonsei University)
Publication Information
Journal of Korea Foundry Society / v.27, no.4, 2007 , pp. 167-172 More about this Journal
Abstract
In the present study, the microstructural evolution and mechanical properties of $Al_{71.6}Ge_{28.4}$ eutectic alloy have been investigated. Stable (fcc ${\alpha}$-Al and diamond cubic ${\beta}$-Ge) and various metastable crystalline (monoclinic, rhombohedral) phases were produced by competitive phase selection during non-equilibrium processing methods i.e. melt spinning and injection casting. The as-injection casted samples containing metastable-equilibrium eutectic (${\alpha}$-Al + monoclinic) structure showed much higher strength than samples with equilibrium eutectic (${\alpha}-Al+{\beta}-Ge$) structure but plasticity disappointingly diminished. In order to endow the enhanced ductility without significant strength drop, the alloys was heat-treated at transition temperature from metastable phase to stable phase. The annealed specimen displayed the phase transformed microstructural evolution and enhanced macroscopic plasticity.
Keywords
Al-Ge eutectic alloy; Non-equilibrium processing; Metastable phase; Strength; Plasticity; Annealing;
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