Use of the Gibbs–Thompson relation to obtain the interfacial energy of δ′ precipitates in Al–Li alloys

The δ′ phase in Al–Li alloys containing 6.4–7.6 at.% Li has been allowed to coarsen for several hundred hours at temperatures of 130–150°C. The size of the δ′ precipitates has been measured by transmission electron microscopy (TEM). The concentration of lithium in solid solution in equilibrium with δ′ particles of various sizes has been measured by an electrical resistivity technique. The resulting TEM and resistivity data are used to solve the Gibbs–Thompson equation to give a value for the α/δ′ interfacial free energy. A value of 0.041±0.01 J m−2 has been obtained for this interfacial energy and this has been compared with the range of values reported in the literature.