Microstructure and Phase Composition of Al–Zn Alloys

Abstract

Structural features, physico-chemical and mechanical properties of a set of Al–Zn alloys have been studied. Precipitates with quasi spherical shape appear in the centre of primary dendrites (10 wt.% and 30 wt.%) and are probably constituted by HCP Zn, and responsible for the improvement of microhardness by mean of dislocation pinup. A high temperature FCC stable solid solution decomposes into a Zn poor FCC solid solution and a hcp solid solution constituted by almost pure Zn. Scanning electron microscopy (SEM) coupled with the EDX analysis determine the precise composition of precipitates with “nuts” shape and it seems that they exhibit a celluar division like behaviour similar to biological mimetic.