Evolution of texture and microstructure in a thermomechanically processed Al-Li-Cu-Mg alloy

Abstract

The development of texture and microstructure in a thermomechanically processed quaternary Al-Li-Cu-Mg alloy has been investigated. Textures on both the surface (1/8 thickness (T)) and midthickness levels of specimens were measured using the conventional pole figure as well as the orientation distribution function (ODF) method. Microstructural characterization was carried out with the help of optical microscopy and transmission electron microscopy (TEM). The processing schedule involved hot cross rolling, followed by several stages of cold rolling (CR) with intermediate solution treatments (STs). A marked through-thickness texture inhomogeneity developed in the processed sheets during the course of thermo mechanical treatment (TMT). In general, the texture produced at the midthickness level was 2 to 3 times sharper than the texture at the surface.

The alloy, after hot cross rolling, showed nearly equally strong Bs {110} 〈112〉 and Bs/S {168} 〈211〉 components at midthickness. After three cycles of cold rolling (CR) and solution treatments (STs), the overall texture intensity came down by a factor of nearly 2. The final processed sheet material showed a moderately strong Bs and a predominant S {123} 〈634〉 component at midthickness. Solution treatments did not produce much change in the texture of the cold-rolled materials. Microstructural evidence indicated extensive recovery and, at best, partial recrystallization of the deformed structure. No significant effect of second-phase particles in texture development was noticed.