Characterization of phase transformations in Al-Li alloys by thermal analysis kinetics

The phase transformations in Al-Li alloys were studied by DSC (differential scanning calorimetry). The phase transformation temperature ranges, types and its microscopic mechanism were ascertained, the kinetics calculating methods of transformations were established and the activation energies of δ' phase precipitation and dissolution were calculated. It is found that the mechanism of δ' phase precipitation is the first reaction, while its dissolution belongs to three dimension diffusion. The activation energies of δ' phase are 188 kJ/mol~214 kJ/mol for precipitation and 158 kJ/mol~228 kJ/mol for dissolution at the conditions of this article. Based on the experiments and analyses, it is regarded that the transformations in Al-Li alloys can be quantitatively characterized by thermal analysis kinetics.