한국주조공학회

The structure and tensile properties of the unidirectionally solidified Al-33wt.%Cu alloy have been investigated. Casted Al-33wt.%Cu alloy was unidirectionally solidified with rates (R) between 1㎝/hr and 24cm/hr maintaining the thermal gradient(G) at solid-liquid interface, 32℃/cm and 21℃/cm. The entectic struture was varied according to the growth condition(G/R radio). When G/R ratio was larger than 8.5x10^3℃/cm^2/sec the lamellar structure was formed, and colony structure was formed when G/R ratio was smaller than 8.5x10^3℃/cm^2/sec. The interlamellar spacing(γ) in the above alloy system was vaired with the growth rate(R) According to "γ^2'R＝8.8x10＾{-11}cm^2/sec" relationship. The yield stress (∑0.001) and UTS for samples in the as-grown condition increased with the interlamellar spacing decrease and the values corresponding to colony structure are lower than those corresponding to amellar structure with the same lamellar spacing. The yield stress for samples in aged condition did not change with the interlamellar spacing.