Origin of through-thickness serrated tensile flow behavior in Al-Cu-Li (AA2195) alloy: Effect of microstructure and texture

Al-Cu-Li alloys are known to exhibit serrated flow behavior, a typical characteristic feature of the dynamic strain aging and the Portevin-Le Chatelier (PLC) effect. In present study, the effect of microstructure and texture on serrated tensile flow behavior in a thick plate of Al-Cu-Li-Mg alloy was investigated. The microstructure consisted of coarse elongated grains with significant texture variation from a {100} < 110 > major component at surface to {110} < 112 > major component at the center layer. Samples from different locations across thickness and orientations were subjected to monotonic tensile loading at different strain rates in solutionized as well as under aged temper conditions. All specimen showed serrations in stress-strain curves, but a decreased serrated intensity from surface to center of the plate. Detailed microstructural examination and texture analysis suggested that the solute-dislocation interaction and shearing of the delta' precipitates could be the possible reasons for the PLC effect in this alloy. The through-thickness anisotropy in strength and serrated flow behavior of the alloy are attributed to the grain morphology and the texture variation in the material.