한국주조공학회

The purpose of this study is to investigate the effect of Be addition on the microstructure and mechanical properties of as-cast and homogenization treated Al-Li-(Be)alloys. The ductility of as-cast Al-Li alloy was increased by the addition of Be and the fracture morphology was changed from brittle to ductile mode. Also, hardness and strength have been decreased by homogenization treatment. The morphology of eutectic structure which consists of α(Al) and α(Be) was changed from lammellae to spherical type by homogenization treatment. The shape of α(Be) phase has been revealed as hollow type by TEM observation. It consists of outer surfaces with well defined crystal facets and the core filled with α(Al). The microstructure of as-cast Al-Li-Be alloys showed coarse δ, fine δ, and coarse δ phases. The coarse and fine δ phases were formed at Be-rich phase /matrix interfaces and in matrix, respectively. By homogenization treatment, the δ phase in Al-Li and Al-Li-Be alloys dissolved and the size of δ phase in Al-Li-Be alloys was finer than that of Al-Li alloy.