Precipitation behavior of extruded AZ80 magnesium alloy subjected to minor tensile deformation

This study investigates the precipitation behavior of an extruded Mg–8Al–0.5Zn (AZ80) alloy subjected to 1.0% tensile deformation along the extrusion direction (ED) to examine the effects of minor slip-inducing deformation on precipitate formation and distribution during aging. The as-homogenized (AH) and pre-tensioned (PT) materials exhibit similar microstructures, including grain size and basal texture, except for a higher dislocation density in the PT material. It was hypothesized that the internal strain energy induced by pre-tension might influence continuous precipitate (CP) formation during aging. However, analysis of factors such as the Schmid factor, kernel average misorientation, and CP features (area fraction, density, and size) across 54 grains reveals no correlation among these variables. Instead, CP bands form unevenly in both AH and PT materials after aging, significantly impacting peak hardness and aging kinetics. These CP bands are not influenced by crystallographic orientation or internal strain energy but are attributed to the non-uniform distribution of Al solute atoms in the extrusion billet. The compositional inhomogeneity of the billet leads to discontinuous precipitate bands in the as-extruded material, which evolve into CP bands during the subsequent aging. Thus, small tensile deformation has minimal influence on precipitation behavior, which is predominantly determined by the inherent inhomogeneity of solute atoms in the billet.