The evolution of elastic strain caused by melting and solidification of small inclusions in Al was investigated by in situ transmission electron microscopy. The appearance and subsequent decay of elastic deformation during phase transformation of inclusions around 100nm in size was observed directly by transmission electron microscopy, and the decay rate was determined as a function of temperature. The activation energy of the process was determined by using alloy composition and inclusion size to control the transformation temperature. Experiments conducted at 150kV showed that elastic strain was accommodated by vacancy diffusion with an activation energy of 1.20eV, in good agreement with the established value of 1.19eV for self-diffusion in high-purity Al. Different rates observed at higher operating voltages were analyzed quantitatively in terms of radiation effects. The self-diffusion coefficient,

D (nm2/s) = 1.55 x 1012 exp[-1.20(eV)/kT]

derived from the present data was in good agreement with accepted values available in the literature.

Observations of Vacancy-Controlled Decay of Elastic Strain Caused by Phase Transformation of Small Pb Inclusions in Al. L.H.Zhang, E.Johnson, U.Dahmen: Acta Materialia, 2005, 53[13], 3635-42