Results were presented on the structure of nano-sized particles (Guinier-Preston and Guinier-Preston-Bagaryatsky zones) in aluminum alloys. Precipitates of alloying elements such as Cu, Mg or Si hindered the motion of dislocations and were thus responsible for the strength of AlCuMg- and AlMgSi-alloys. The role of quenched-in vacancies in diffusive motion at room temperature in enabling the growth of the precipitates was considered. Using positron annihilation spectroscopy, both lifetime and Doppler broadening, furnished information on the local atomic environment in the vicinity of vacancies. On the other hand, X-ray absorption fine structure spectroscopy was capable of characterizing the local atomic environment around selected elements (Cu, Mg). The measured data were interpreted by comparing them to numerical calculations of positron annihilation spectroscopy and X-ray absorption fine structure spectroscopy spectra. However, reliable numerical calculations of spectroscopic quantities were only possible provided that relaxed atomic positions were used as an input. Those were calculated using ab initio code. Thus, considering the decomposition of Al-alloys, extremely valuable information was obtained on the earliest stages, forming immediately after solution heat treatment and quenching, i.e. during the first few minutes of storage at room temperature.

Atomic Structure of Pre-Guinier-Preston and Guinier-Preston-Bagaryatsky Zones in Al-Alloys. T.E.M.Staab, B.Klobes, I.Kohlbach, B.Korff, M.Haaks, E.Dudzik, K.Maier: Journal of Physics - Conference Series, 2011, 265[1], 012018