Fine Scale Precipitates in Al-Mg-Zn Alloys after Various Aging Temperatures

Nasser Afify, Abdel-Fattah Gaber, Ghada Abbady

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DOI: 10.4236/msa.2011.25056                

Abstract

This article deals with investigation of fine-scale precipitation in Al-Mg-Zn alloys with compositions of Al - 2 at% Mg- x at% Zn, (x = 1.8, 2 and 4.2). The precipitates morphology was examined by scanning electron microscope (SEM) and correlated with the microhardness (HV) and differential scanning calorimetry (DSC) of the specimens. The precipitates are characterized as h’ (MgZn2) and h (MgZn₂) phases of hexagonal structure of the same composition with a slight difference in lattice parameters. In addition, T-phase pf composition (Mg₃₂ (Al, Zn)₄₉) having a cubic crystal structure. Owing to the determined activation energies of the precipitates, the kinetics associated with their nucleation and growth can be characterized. The thermal energy acquired during aging leads to the agglomeration of precipitates to or larger particle sizes.

Keywords

Al-Mg-Zn Alloys, Coherent Precipitates, Aging, Microhardness, Scanning Electron Microscopy, Precipitation Kinetics

Conflicts of Interest

The authors declare no conflicts of interest.

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