Characterization of the effects of different tempers and aging temperatures on the precipitation behavior of Al-Mg (5.25at.%)-Mn alloys

Publication date: 15 March 2017
Source:Materials & Design, Volume 118
Author(s): Gaosong Yi, Kenneth C. Littrell, Jonathan D. Poplawsky, David A. Cullen, Erik Sundberg, Michael L. Free
The effects of different tempers (H131 and H116) and different aging temperatures (50 and 70°C) on the precipitation behavior of Al-Mg (5.25at.%)-Mn (Al 5083) alloys aged for a long time (41 and 30months) were investigated using electron backscatter diffraction(EBSD), scanning transmission electron microscopy(STEM), energy-dispersive X-ray spectroscopy(EDS), atom probe tomography (APT), and small angle neutron scattering (SANS). GP zones and β″ phases were found in Al 5083 H116 aged at 50°C for 24months using APT. EDS and SANS results revealed that a phase transformation process from GP zones to β′/β phases occurred for precipitates formed in both Al 5083 H131 and H116 aged at 70°C. The effective diffusion coefficient of Mg in Al 5083 H131 is 1.8 times of that in Al 5083 H116 aged at 70°C. The precipitation process in Al 5083 H116 aged at 50°C is much slower than that in the sample aged at 70°C. The coarsening process was identified in Al 5083 H131 and H116 aged at 70°C for >9months.

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