Fabrication methods to manufacture isotropic Al-Li alloys and products for space and aerospace applications

After a description of the evolution of Al-Li alloys, this paper first reviews the subject of anisotropy in mechanical properties of Al-Li wrought products. In plane, through thickness and axisymmetric flow anisotropies present in Al-Li wrought products are defined. The root causes for these anisotropies are discussed. Pros and cons arising from anisotropic products are then discussed in the context of designing and manufacturing for space and aerospace structures. Numerous attempts aimed to reduce anisotropy in rolled and extruded products are summarized. It is concluded that ‘isotropic’ Al-Li products can be manufactured via the selection of appropriate process, composition and processing parameters.