급냉응고된 Al-Li-Cu 합금의 열처리, 미세조직 및 기계적 성질에 관한 연구 (2) = Heat-Treatment, Microstructure and Mechanical Properties Rapidly Solidified Al-Li-Cu Alloy (2)

다국어 초록 (Multilingual Abstract)

In this study the microstructures of rapidly solidified Al-4Li-2Cu, Al-4Li-2Cu-0.3Zr alloy powders and the mechanical properties of extrudates have been investigated. The alloy powders have been prepared by means of gas atomization technique. Rapidly solidified alloy powders show the icosahedral intermetallic compounds of five-fold symmetry which are randomly distributed in cell-boundaries of α matrix. Both of these alloy powders, heat-treated at 200℃ for 1 hour have fine δ' phases homogeneousy precipitated throughout the matrix. The precipitation of δ' phase within the α matrix increases the microhardness. After the heat-treatment at 300℃ for 1 hour, all the δ' phases has been transformed to icosahedral intermetallic compounds. Room temperature tensile strength of Al-L₁-Cu and Al-Li-Cu-Zr extrudates are 325MPa, 350MPa, respectively. Under the isothermal aging condition at 180℃, Al₃Li & A1₃Zr are precipitated in the matrix. The tensile strength of Al-Li-Cu extrudate is 425 MPa and that of Al-Li-u-Zr extrudate is 430MPa after 24 hours isothermal aging at 180℃