Overview on the Microstructure and Mechanical Properties of Ultrafine-grained Al-Li Alloys Produced by Severe Plastic Deformation

This review reveals microstructure and mechanical properties of Al-Li alloys produced by SPD (severe plastic deformation) techniques. It focuses on the microstructure evolution during SPD, with the influence of internal and external factors. The strengthening mechanism of Al-Li alloy, mainly based on precipitation hardening, is presented. It is demonstrated that UFG (bulk ultrafine-grained) Al-Li may attain enhanced strength with relatively good ductility via grain refinement and multiple precipitates. Special attention is given to the superplasticity of UFG Al-Li alloys, especially to the high strain rate superplasticity (HSR SP). It suggests that UFG Al-Mg-Li alloy produced by SPD, particularly by equal-channel angular pressing (ECAP), is a promising candidate material for use in superplastic forming operations.