Annealing kinetics of voids and the Self‐diffusion coefficient in aluminum

The annealing kinetics of voids in 99.9999 wt% pure aluminum were studied over the temperature range 85 to 209 °C in thin specimens by transmission electron microscopy. The isothermal shrinkage of individual voids was measured and interpreted on the basis of a self‐diffusion annealing model. The self‐diffusion coefficient of aluminum, as determined from the data, was given by D s = 0.176 exp (‐1.31 eV/ kt ) cm 2 s −1 . The activation energy, Q = 1.31 eV, is significantly lower than the value Q = 1.48 eV determined by Lundy and Murdock at temperatures near the melting point in the only reported measurement by the radioactive tracer technique. Considerable evidence from a variety of sources is discussed which tends to support the present result.