Strengthening mechanisms in an Al–Mg alloy

Recent improvements in strength and ductility of 5083 aluminum alloys have been obtained through the development of complex microstructures containing either reduced grain sizes (ultra-fine and nano-grained materials), grain size distributions (bimodal microstructures), particle reinforcements, or combinations of the above. Optimization of such microstructures requires an understanding of the conventional, coarse-grained basis alloy. We present here a complete experimental data set for conventional Al-5083 H-131, with primary alloying element Mg (4.77 wt%) and secondary element Mn (0.68 wt%) in compression over a range of strain rates (10−4–6000 s−1) at room temperature. The various strengthening mechanisms in Al-5083 are explored, including solute strengthening, precipitate hardening, strain hardening, strain rate hardening, and strengthening due to dislocation sub-structures. Previous experiments found in the literature on Al–Mg binary alloys allow us to calculate the solute strengthening due to Mg in solid solution, and TEM analysis provides information about precipitate hardening and dislocation cell structures. A basic strength model including these strengthening mechanisms is suggested.