In this study, microstructures of age-hardened 2014 Al alloy forged by cold biaxial alternate forging was investigated by transmission electron microscope. And also, the forming limits of age-hardened 2014 Al alloy were examined using both conventional compression test and biaxial alternate forging. As a result of compression test, it showed a perfect plastic behavior with no visible change in stress after 27% in strain and eventually, the curve fluctuated as a shear crack occurs after 51% strain. However, it was possible to impose very large strains on the 2014-T6 Al alloy workpieces through the biaxial alternate forging of up to 4 passes. The effective strain was possibly accumulated to 356% and 204% as the maximum and average values, respectively. The results of transmission electron microscope indicated that the high density dislocations were distributed after 3 passes. After 4 passes, the distribution of more increased dislocations was observed and band-shaped dislocation clustering appeared.

In this study, precipitation of Ca in Al-Mg alloys containing a trace of Ca during homogenization was investigated using a transmission electron microscope (TEM) and calculated phase diagrams. TEM result indicated that the Ca-based particles found in the examined sample are Ca7Mg7.5Si14. From the calculation of Scheil-Gulliver cooling, it was found that the Ca was formed as Al4Ca and C36 laves phases with Mg2Si and Al13Fe4 from other impurities phase during solidification. No Ca-Mg-Si ternary phase existed at the homogenization temperature in the calculated phase diagram. From the phase diagram of Al-Al4Ca-Mg2Si three-phase isothermal at 490℃, it was shown that Ca7Mg6Si14 phase co-exists with Al, Mg2Si and Al4Ca in the largest region and with only Al and Mg2Si in Al4Ca-poor regions. It was thought that the Ca7Mg6Si14 ternary phase was formed by the interaction between Mg2Si and Al4Ca considering that the segregation can occur throughout the entire microstructures.