Microstructural Evolution of 7012 Alloy During the Early Stages of Artificial Ageing.

R. FERRAGUT; A. SOMOZA; A. TOLLEY

ACTA MATERIALIA

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1999 vol. 47 p. 4355 - 4364

1359-6454

A study of the microstructural evolution of a commercial 7012 (Al±Zn±Mg±Cu) age-hardenablealloy following arti®cial ageing by high resolution and conventional transmission electron microscopy andpositron annihilation lifetime spectroscopy is presented. At the early stages of decomposition, the micro-structure included precipitation of either pre-precipitate solute clusters or Guinier±Preston zones and semi-coherent Z' precipitates, with typical sizes between 1 and 10 nm. Quantitative information on the size,number density and morphology of the particles present in the microstructure was obtained. The resultswere correlated with those obtained using positron annihilation lifetime spectroscopy.