| Precipitation structure, physical and mechanical properties have been examined in Al-Cu-Li-Mg-Ag-Zr(Cl) and Al-Li-Cu-Zr(2090) alloys using hardness and density measurement, tensile test, transmission electron microscopy. And, in an attempt to assess the composition of precipitate, energy dispersive X-rey microanalysis was performed using the scanning transmission electron microscopy technique. The tensile strength 630MPa, density 2.69g /㎤, hardness number H_RB 96 and specific strength extremely exceeding that of 2090 and 7075-T6 alloy are achived. In the near peak-aged condition, finer and homogeneous distribution of θ` and T₁, phases than that of an 2090 alloy were precipitated and due to small amount of Mg addition, S` phase in Al-Cu-Mg alloy was precipitated. Energy dispersive X-ray spectra microanalysis was performed on the relatively coarse black particle obserbed in the matrix and matrix phase. The result of EDXS microanalysis, the X-ray spectrum from the matrix reveals Al and Cu peak but black particle reveals Al, Cu and Ag peak which does not reveal from the matrix. |
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